clean up getplaceholdervalue

Global_Indexer/ClassControls.vb

@@ -374,7 +374,7 @@ Public Class ClassControls
             }
         }
 
-        If Vorgabe.ToUpper = "NULL" Then
+        If Vorgabe.ToUpper = "$NULL" Then
             oPicker.EditValue = Nothing
         ElseIf Vorgabe IsNot Nothing Then
             oPicker.EditValue = Vorgabe

Global_Indexer/frmAdministration.vb

@@ -1314,7 +1314,7 @@ Public Class frmAdministration
                 Case 5 : oValue = "$DateDDMMYYY"
                 Case 6 : oValue = "$Username"
                 Case 7 : oValue = "$Usercode"
-                Case 8 : oValue = "NULL"
+                Case 8 : oValue = "$Null"
             End Select
 
             DEFAULT_VALUETextBox.Text = oValue

Global_Indexer/frmIndex.vb

@@ -1728,8 +1728,8 @@ Public Class frmIndex
         End Try
     End Sub
 
-    Function GetPlaceholderValue(InputValue As String, FileName As String, UserShortName As String)
-        Dim oResult = Nothing
+    Function GetPlaceholderValue(InputValue As String, FileName As String, UserShortName As String) As String
+        Dim oResult As String
 
         Try
             Select Case InputValue.ToString.ToUpper