You don't need the single quotes, but because of the / in the field name, you might need brackets. Try this first:
VB Code:
  1. sSQL = "SELECT Callsign/Station FROM tbl_master
Single quotes are needed around string data elements, not field or table names.

If that still gives you heartburn, but brackets around Callsign/Station (i.e., [Callsign/Station] )