Update Assign to field with Outlook vbs - vba

Question

In the Outlook i have create a custom form in Task form. I use it to assign task to other users. Now i try to add some code when a user not fill the assign to field (for example if the task is for him to check it when save the task and ask him if need to add himself as assigned user. My problem is that i can't update the field assigned to if it's empty.I get the error My code is the following:
Sub Item_Write(ByVal Name)
Set objPage = Item.GetInspector.ModifiedFormPages("Assign Task")
Set objControl = objPage.Controls("RecipientControl1")
Set objControl2 = objPage.Controls("Textbox1")
Set objControl4 = objPage.Controls("Textbox4")
Set oMsg = Application.CreateItem(olMailItem)
Set objNS = oMsg.Session
MyValue= objControl2.Value
MyValue4= objControl4.Value
if MyValue= "" then
if Msgbox ("Task isn't assign to anybody. Do you want to assign yourself?", vbYesNo)=vbYes then
objControl.Value=objNS.CurrentUser.Name
End if
End if
End Sub

Answer 1

Finally i found the solution,
I use the event Item_Close and Outlook property name for Recipient control and not Control name in Vbs. Find below my code that is working and form not close until user assign the task someone.
Function Item_Close()
Set objPage = Item.GetInspector.ModifiedFormPages("Assign Task")
Set objControl = objPage.Controls("Textbox1")
Set objNS = Application.GetNamespace("MAPI")
Set objContro2 = objPage.Controls("Frame1")
assigned=objControl.Value
'Use always Outlook property names and not Control Properties(as RecipientControl in case)
if assigned= "" then
info =Msgbox ("The task is not assigned to a user. Do you want to assign yourself?", vbYesNo)
Select Case info
Case 6
'Use always Outlook property names and not Control Properties(as RecipientControl in case)
Set myAssignedTo = Item.Recipients.Add(objNS.CurrentUser.Name)
Me.Save
Case 7
MsgBox "You must Assign Task to a user before save it.", vbExclamation
Item_Close=False
Item.GetInspector.SetCurrentFormPage "Assign Task"
End Select
End if
End Function