Hi

A couple of things.  Firstly you can use a conditional statement and use the
visible property of the form.  Secondly for a message, you can either use a
label on the form that is hidden normally and you display it when
appropriate, or you can use a pop up message box.

There are a couple of ways to check if there are records.  One is to do a
record count and if it is zero, fire up the message and hide the fields.  
Once again I use a generic function to count records.  I just pass the SQL
statement and it returns the number of records.  You could use this for the
On Current event.

Dim strSQL as String

strSQL = "SELECT * from tblLetters where tblLetters.ClientNo = " &
Forms!frmClient!ClientNo

If funRecordCount (strSQL)>0 then  ' Records exist
   Me!txtClientName.Visible = True   ' Add any fields you want to make
visible
   Me!lblCustomWarning.Visible = False        ' Hide the warning message
 Else
   Me!txtClientName.Visible = False  ' Hide any fields
   Me!lblCustomWarning.Visible = True  ' Display the warning
End If

The function for funRecordCount can be stored in a module.

Public Function funRecordCount(strSQL As String) As Integer
   Dim dbs As Database
   Dim rst As Recordset
       
   On Error GoTo Error_funRecordCount

   Set dbs = CurrentDb
   Set rst = dbs.OpenRecordset(strSQL, dbOpenSnapshot, dbSeeChanges)
   
   ' Find the number of records.  First test records were found.
   If (rst.EOF = True) And (rst.BOF = True) Then
       funRecordCount = 0                                          ' No
records found
      Else
       rst.MoveLast                                                ' End of
the recordset
       funRecordCount = rst.RecordCount                            ' Number
of records
   End If
   
Exit_funRecordCount:
   On Error GoTo 0
   Set dbs = Nothing
   Set rst = Nothing
   Exit Function

Error_funRecordCount:
   MsgBox "An unexpected situation arose in your program." & funCrLf & _
          "Please write down the following details:" & funCrLf & funCrLf & _
          "Module Name: modGeneric" & funCrLf & _
          "Type: Module" & funCrLf & _
          "Calling Procedure: funRecordCount" & funCrLf & _
          "Error Number: " & Err.Number & funCrLf & _
          "Error Descritption: " & Err.Description
         
   Resume Exit_funRecordCount

End Function