SAP's messagbox blocks add event

Question

Dear All,
I have put some user choice through SAP's message box on the add click event of sales order form. if user selects 'No', I dont let him add it. if he selectes 'Yes' button, the sales order should execute normal addition with its default addition. but nothing happens after the user clicks any button. it seems the appearance of messagebox blocks the add event. what should I do??
the code is :
If (pVal.FormType = "139" And pVal.ItemUID = "1" And pVal.EventType = SAPbouiCOM.BoEventTypes.et_CLICK And pVal.Before_Action = True) Then
                oform = Nstk_Application.Forms.GetForm(pVal.FormType, pVal.FormTypeCount)
                ocombo = oform.Items.Item("ExpDoc").Specific
                Dim SaveSO As Integer
                Try
                    SaveSO = Nstk_Application.MessageBox("Do you want to save this Sales order without LC Details?", 2, "Yes", "No")
                    If SaveSO = 2 Then
                        BubbleEvent = False
                    End If
                Catch ex As Exception
                    MsgBox(ex.Message)
                End Try
            End If
if I put simple msgbox instead of SAP's messagebox, the "Add" is triggered.
Thanks,

Answer 1

Hi Kevin,
Sorry about the late reply.
Here what SAP replied to me:
Statement from Harshavardhan Jegadeesan (SAP): 
"We are working on an official presentation. For now we can send an executive summary:
1  SAP Event Management is a track & trace solution in the Supply Chain space.
SAP Operational Process Intelligence is a native HANA solution for operational intelligence and process management.
2  Both solutions are complimentary and can help customers gain visibility, manage by exceptions and ensure business processes are running as per plan.
3  SAP will support to extend track & trace scenarios built with SAP Event Management seamlessly with operational intelligence, predictive
analytics, real-time analytics and KPIs, business situation detection with business rules and remedial actions with SAP Operational Process Intelligence in HANA."
Our Company is still in the process of gathering Business Requirements. Once that is completed we will decide which route to go.
Maybe both, i.e. utilizing EM for certain functions  and  OpInt  for others  according to business needs.
Cheers,
Jo.