This Works: =MsgSvc('MustKeyEntered')
This does not: =MsgSvc('MustKeyEntered', mytext + '~' + 'continuing') where mytext is filled with a field name. When MsgSvc receives this it treats it as on long string in Parm1, Parm2 and Parm 3 are false ..."

Does seem like an odd one.

1.) msgsvc()'s index seeking is based on upper(ckey), so make sure that is how your index is constructed.
2.) If that look's ok, just put a suspend in msgsvc.prg and step thru with the debugger turned on and watch what happens. That will tell you where things blow up.

Kevin