hi
i was interfacing a 4x4 keyboard to my 8252 . i was connecting the rows to p1.0 to p1.3 and coloumns to p1.4 to p1.7
i had the same problem that all the keys wer not being detected .i guess you have the same problem .. as in not multiple key press but not detecting all the keys pressed.. it was able to detect a set of keys but unable to detect the remaining keys

i suggest you check your code as i was making some mistake in the code.
Regards
-Vishal