I'm using Firebird-1.5.2.4731, and client IBExpert.
According to http://www.destructor.de/firebird/1.5/case.txt, i have
implemented following case query(here part of the query),
But same error msg is giving and not executing.

case
when MP.RoleID = -1 then 'All Users'
when MP.RoleID = -2 then 'Superuser'
when MP.RoleID = -3 then 'Unauthenticated Users'
else R.RoleName
end

I can't see any problem, but why not executing, any comment???