[CutX]

show us the definition of "PRESSED"
as on the wiki page, it should look like

pawn Код:

#define PRESSED(%0) \
(((newkeys & (%0)) == (%0)) && ((oldkeys & (%0)) != (%0)))

or

pawn Код:

#define PRESSED(%0) (((newkeys & (%0)) == (%0)) && ((oldkeys & (%0)) != (%0)))

cuz for example, if it's defined incorrectly, you'll get exactly that error.
by incorrectly i mean something like this, copy&paste from wiki but without the "\"

pawn Код:

#define PRESSED(%0) 
    (((newkeys & (%0)) == (%0)) && ((oldkeys & (%0)) != (%0)))

but in this example, thou also get " error 010: invalid function or declaration"
pointing at the line under the definition of "PRESSED".

so you might've messed up something above your code too.

but "invalid expression, assumed zero" simply means that
the compiler could not interpret that expression so im sure that there's
something wrong with your definition of "PRESSED"