Checking database fields for no data

[Tomexx]

My program reads Access DB table. I use the following code to make sure I only read the field if the data is there:

  If (rs.Fields("COMMNT1") <> vbNull) Then
    strCOMMNT1 = Trim(rs.Fields("COMMNT1"))
  End if

However if the field is empty I get an error on the vbNull line. I'm thinking checking against the vbNull is not the right way to do it. How do I check for an empty field?