runtime error 91 object variable or With block var

问题:

I have activex dll which has code for message queue, read and write from remote as well as local machine. i did some changes for reading messages from remote queue and tested that dll with sample form application. which works fine however when i copied this dll to my test machine (in actual application) i am facing "runtime error 91 object variable or With block variable not set" error

if i revert my changes its working fine

code after changes

Private Function RetrieveMessage(ByVal MQReceive As msmq.MSMQQueue, _
MQTransaction As msmq.MSMQTransaction, _
ByVal Wait As Boolean, MessageLabel As String, MessageBody As String) As Boolean

'Dim MQReceive As MSMQ.MSMQQueue
Dim MQMsgRec As MSMQMessage
Dim MQDispenser As msmq.MSMQCoordinatedTransactionDispenser

On Error GoTo ErrorHandler

RetrieveMessage = False

If Not m_bQueueExists Then
    Err.Raise vbObjectError + 1, "MicrosoftMQImpl", "Queue " & m_sQueueName & _
    " does not exist"
Else
  Set MQDispenser = New msmq.MSMQCoordinatedTransactionDispenser
    'Begin Transaction
    Set MQTransaction = MQDispenser.BeginTransaction

    Dim bMessageFound As Boolean
    bMessageFound = False

    Set MQMsgRec = MQReceive.Receive(ReceiveTimeout:=IIf(Wait = True, DISPATCH_MESSAGE_INTERVAL, 0))

    'Set MQMsgRec = MQReceive.Receive(Transaction:=MQTransaction, _
       ' ReceiveTimeout:=IIf(Wait = True, DISPATCH_MESSAGE_INTERVAL, 0))

    If MQMsgRec Is Nothing Then
        bMessageFound = False
    Else
        bMessageFound = True
        MessageBody = CStr(MQMsgRec.Body)
        MessageLabel = CStr(MQMsgRec.Label)
    End If

    Set MQDispenser = Nothing
    Set MQMsgRec = Nothing

    RetrieveMessage = bMessageFound

    MQTransaction.Commit
    Set MQTransaction = Nothing

End If
Exit Function
ErrorHandler:
If Not (MQTransaction Is Nothing) Then
    MQTransaction.Abort
    Set MQTransaction = Nothing
End If
LogNTEvent "PHLMessaging:MicrosoftMQImpl:RetrieveMessage", Err.Description, eNTLog_Error
Err.Raise Err.Number, Err.Source, Err.Description
End Function

code before changes

Private Function RetrieveMessage(ByVal MQReceive As msmq.MSMQQueue, _
MQTransaction As msmq.MSMQTransaction, _
ByVal Wait As Boolean, MessageLabel As String, MessageBody As String) As Boolean

'Dim MQReceive As MSMQ.MSMQQueue
Dim MQMsgRec As MSMQMessage
Dim MQDispenser As msmq.MSMQTransactionDispenser

On Error GoTo ErrorHandler

RetrieveMessage = False

If Not m_bQueueExists Then
    Err.Raise vbObjectError + 1, "MicrosoftMQImpl", "Queue " & m_sQueueName & _
    " does not exist"
Else
Set MQDispenser = New msmq.MSMQTransactionDispenser
    'Begin Transaction
    Set MQTransaction = MQDispenser.BeginTransaction

    Dim bMessageFound As Boolean
    bMessageFound = False


    Set MQMsgRec = MQReceive.Receive(Transaction:=MQTransaction, _
        ReceiveTimeout:=IIf(Wait = True, DISPATCH_MESSAGE_INTERVAL, 0))

    If MQMsgRec Is Nothing Then
        bMessageFound = False
    Else
        bMessageFound = True
        MessageBody = CStr(MQMsgRec.Body)
        MessageLabel = CStr(MQMsgRec.Label)
    End If

    Set MQDispenser = Nothing
    Set MQMsgRec = Nothing

    RetrieveMessage = bMessageFound

End If
Exit Function
ErrorHandler:
If Not (MQTransaction Is Nothing) Then
    MQTransaction.Abort
    Set MQTransaction = Nothing
End If
LogNTEvent "PHLMessaging:MicrosoftMQImpl:RetrieveMessage", Err.Description, eNTLog_Error
Err.Raise Err.Number, Err.Source, Err.Description
End Function

Thanks in advance

回答1:

i somehow managed to resolve this error just commented following code in changes

MQTransaction.Commit
Set MQTransaction = Nothing

still dont know why :-|