InvalidOperationExpression was unhandled by user code(Enterprise Library)

[EliteBrain]

Public Function GetMaxSerialNumber(ByVal docType) As Int32

      Dim db As Database = DatabaseFactory.CreateDatabase("igrwebConnectionString")

      Dim sqlCommand As String = SP\_UPDATE\_DOCUMENTDETAILS
      Dim dbCommand As DbCommand = db.GetStoredProcCommand(sqlCommand)
      db.AddInParameter(dbCommand, "@operationType", DbType.String, "R")
      db.AddInParameter(dbCommand, "@cType", DbType.Int64, docType)

      Dim SrNo As Integer = db.ExecuteScalar(dbCommand)
      Return SrNo + 1

  End Function

The above code is giving an exception at db.ExecuteScalar(dbCommand) Error is

ExecuteScalar requires the command to have a transaction when the connection assigned to the command is in a pending local transaction. The Transaction property of the command has not been initialized.

Please Help as i am new to enterprise library

[JV9999]

As the exception says you need to instantiate a transaction in your code (which you aren't doing at this moment). That will fix your issue.