Cannot convert value "......." to type

Question

I'm running the following script on Exchange 2010. The script reads 3 text files and then removes everyone from the Distribution Group / Universal Distribution Group  "Messages Delivery Restrictions - Accept Messages Only From" before adding
a new list of users
$People = gc C:\ps_scripts\Staff_Aliases.txt
$UDGroups = gc C:\ps_scripts\Universal_Distribution_Groups.txt
$DDGroups = gc C:\ps_scripts\Dynamic_Distribution_Groups.txt
ForEach ($UDGroup in $UDGroups) {
   Set-DistributionGroup $UDGroup -AcceptMessagesOnlyFrom $null
   Set-DistributionGroup $UDGroup -AcceptMessagesOnlyFrom((Get-DistributionGroup $UDGroup).AcceptMessagesOnlyFrom + $People)
ForEach ($DDGroup in $DDGroups) {
   Set-DynamicDistributionGroup $DDGroup -AcceptMessagesOnlyFrom $null
   Set-DynamicDistributionGroup $DDGroup -AcceptMessagesOnlyFrom((Get-DistributionGroup $DDGroup).AcceptMessagesOnlyFrom + $People)
and I'm getting the following error:
Cannot convert value "a.abcd h.qwerty staff-abc staff.bcd" to type "Microsoft.Exchange.Data.MultiValuedProperty`1[Microsoft.Exchange.Configuration.Tasks.DeliveryRecipientIdParameter
]". Error: "Cannot convert value "" to type "Microsoft.Exchange.Configuration.Tasks.DeliveryRecipientIdParameter". Error: "Parameter values of type Microsoft.Exchange.Configuration.Tasks.DeliveryRecipientIdParameter can't
be empty. Specify a value, and try again.
Parameter name: identity""
    + CategoryInfo          : InvalidData: (:) [Set-DynamicDistributionGroup], ParameterBindin...mationException
    + FullyQualifiedErrorId : ParameterArgumentTransformationError,Set-DynamicDistributionGroup
I'm getting the content from three text files, the first contains the User Alias and the 2nd/3rd contain the Universal and Dynamic Distribution Groups.
This is an exact copy and paste from the EMC screen and I know that the script should work but I can't see what I'm doing wrong
Help or ideas please
Darryn

Answer 1

Set-DynamicDistributionGroup $DDGroup -AcceptMessagesOnlyFrom((Get-DistributionGroup $DDGroup).AcceptMessagesOnlyFrom + $People)
Look closely at this line.  Read the documentation to see how it is used.
What you h ave typed makes no sense and I cannot understand what you want to do with this.
Start here for a tutorial on how to use these CmdLets:
http://blogs.msdn.com/b/ukeducloud/archive/2011/10/05/dynamic-distribution-groups-part-1.aspx
http://blogs.technet.com/b/educloud/archive/2011/10/06/dynamic-distribution-groups-part-2.aspx
¯\_(ツ)_/¯