Getting invalid-attribute-value Error during Delta Import on Call-based ECMA2

Question

I'm developing an ECMA2 MA to which supports delta imports.  I have found very few samples of working code to do delta imports, so my attempts are created
using a lot of trial and error... Any samples of working Call based MA's with delta support would be much appreciated :-)
The data is located in a SQL server and the schema (for delta) is like this (simplified):
EmpID string
Status string
UPDATESTATUS string (<-- This is the update column with values New/Update/Delete)
For each EmpID, there may be multiple Status values, i.e. Status should be imported into a multi value attribute in FIM.
For the full import this is working as expected, but I run into issues when attempting to do the delta imports
The code for the delta import
private
GetImportEntriesResults GetImportEntries_Delta(GetImportEntriesRunStep importRunStep)
GetImportEntriesResults importReturnInfo;
List<CSEntryChange> csentries =
new List<CSEntryChange>();
string employeeID =
null;
string appStatus =
null;
string currEmployeeID =
CSEntryChange csentry =
null;
List<string> appStatusList =
new List<string>();
string changeMode =
for (int i = currentReadRecord; i <= da.Tables["AppStatus"].Rows.Count - 1; i++)
if (currEmployeeID != da.Tables["AppStatus"].Rows[i].ItemArray.GetValue(0).ToString().Trim())
if (currEmployeeID !=
"") // this should be true except for the first run
csentry.AttributeChanges.Add(AttributeChange.CreateAttributeUpdate("IdentityStores", appStatusList));
csentries.Add(csentry);
appStatusList = new
List<string>();
if (csentries.Count >= m_importPageSize)
              currentReadRecord = i;
importReturnInfo = new
GetImportEntriesResults();
importReturnInfo.MoreToImport = (i <= da.Tables["AppStatus"].Rows.Count - 1);
importReturnInfo.CSEntries = csentries;
return importReturnInfo;
changeMode = da.Tables["AppStatus"].Rows[i].ItemArray.GetValue(2).ToString().Trim();
csentry = CSEntryChange.Create();
csentry.ObjectType = "ApplicationIdentity";
employeeID = da.Tables["AppStatus"].Rows[i].ItemArray.GetValue(0).ToString().Trim();
currEmployeeID = (string)employeeID;
switch (changeMode)
case "New":
csentry.ObjectModificationType = ObjectModificationType.Add;
csentry.AttributeChanges.Add(AttributeChange.CreateAttributeAdd("EmployeeID", employeeID));
break;
case "Update":
csentry.ObjectModificationType = ObjectModificationType.Update;
csentry.DN = employeeID;
break;
case "Delete":
csentry.ObjectModificationType = ObjectModificationType.Delete;
                     csentry.DN = employeeID;
break;
default:
throw new
UnexpectedDataException(string.Format("Unknown modification type: {0}", changeMode));
appStatus = da.Tables["AppStatus"].Rows[i].ItemArray.GetValue(1).ToString().Trim();
appStatusList.Add(appStatus);
// save the last object
if (csentry != null)
csentry.AttributeChanges.Add(AttributeChange.CreateAttributeUpdate("IdentityStores", appStatusList));
csentries.Add(csentry);
importReturnInfo = new
GetImportEntriesResults();
importReturnInfo.MoreToImport = false;
importReturnInfo.CSEntries = csentries;
return importReturnInfo;
The code compiles and executes, but the delta import fails with the "invalid-attribute-value" message per csentry.
From the eventlog I have the following message
The server encountered an unexpected error while performing an operation for a management agent.
"System.InvalidCastException: Unable to cast object of type 'System.Collections.Generic.List`1[System.String]' to type 'System.String'.
   at Microsoft.MetadirectoryServices.Impl.Ecma2ConversionServices.AddAttributeToDImage(CDImage* pdimage, String attributeName, AttributeModificationType
attributeModificationType, IList`1 attributeValueChanges, Int32 escapeReferenceDNValues)
   at Microsoft.MetadirectoryServices.Impl.Ecma2ConversionServices.ConvertToDImage(CSEntryChange csEntryChange, CDImage** ppDImage, Int32 escapeReferenceDNValues)
   at Microsoft.MetadirectoryServices.Impl.ScriptHost.InvokeExtMA_ImportEntry(UInt32 cBatchSize, UInt16* pcszCustomData, UInt32 cFullObject,
_OCTET* rgoctFullObject, UInt32* rgomodt, UInt32* pcpcszChangedAttributes, UInt16*** prgpcszChangedAttributes, Int32 fIsDNStyleNone, UInt16** ppszUpdatedCustomData, _OCTET* rgoctCSImage, Int32* rgextec, UInt16** rgpszErrorName, UInt16** rgpszErrorDetail, Int32*
pfMoreToImport)"
To me it seems as if FIM is unable to process the List of strings that is returned when processing the delta. Remember that this works OK when doing the full import. 
Do you have any suggestions as to why this fails?
Kjetil

Answer 1

Hi,
Thank you Søren! I got some good clues for the right direction from your answer. If anyone would be looking same answers the correct solution would be down below. I hope it would be help for someone else too.
Get-Shema.ps1
$obj
= New-Object
-Type PSCustomObject
$obj
| Add-Member
-Type NoteProperty
-Name "Anchor-Id|String"
-Value 1
$obj
| Add-Member
-Type NoteProperty
-Name "objectClass|String"
-Value "user"
$Obj
| Add-Member
-Type NoteProperty
-Name "IsLicensed|Boolean"
-Value $true
$Obj
| Add-Member
-Type NoteProperty
-Name "FirstName|String"
-Value ""
$Obj
| Add-Member
-Type NoteProperty
-Name "LastName|String"
-Value ""
$Obj
| Add-Member
-Type NoteProperty
-Name "mail|String"
-Value ""
$Obj
| Add-Member
-Type NoteProperty
-Name "immutableId|String"
-Value ""
$Obj
| Add-Member
-Type NoteProperty
-Name "DisplayName|String"
-Value ""
$Obj
| Add-Member
-Type NoteProperty
-Name "UsageLocation|String"
-Value ""
$Obj
| Add-Member
-Type NoteProperty
-Name "ProxyAddresses|String[]"
-Value ("","")
$Obj
| Add-Member
-Type NoteProperty
-Name "Licenses|String[]"
-Value ("","")
$obj
Import.ps1
#Always pass objects as hash table in pipeline
foreach ($User
in $Users)
$obj = @{}
$obj.Add("Id",
$User.UserPrincipalName)
$obj.Add("objectClass",
"user")
$obj.Add("IsLicensed",
$User.IsLicensed)
$obj.Add("FirstName",
$User.FirstName)
$obj.Add("LastName",
$User.LastName)
$obj.Add("mail",
$User.UserPrincipalName)
$obj.Add("immutableId",
$User.immutableId)
$obj.Add("DisplayName",
$User.DisplayName)
$obj.Add("UsageLocation",
$User.UsageLocation)
$obj.Add("ProxyAddresses", ($User.ProxyAddresses
-ne ""))
$obj.add("Licenses", ($User.Licenses.AccountSkuId))
$obj
Marti