hmm, i expect your char prolly has more than 10 INT, but anyhoo:
A wizard needs 10 INT at least to cast lvl 1 spells, 11 INT to cast lvl 2 spells etc. SO if your char has 9 int no spells for you.
Same goes for clerics and wisdom btw.
Can't think of other reasons.
P.S. i'm a bit rusty on 3d edition AD&D so it could well be 11 INT to cast lvl spells, 12 for lvl 2 etc.