Mage Armor does not work at all, even when casted on someone with no armor.

I've had this same problem several times now. (and all the time as far as I can tell)

My AC ends up being only 1 pt higher than what my char's AC with Dex bonus should be.

He has no other bonuses from items or armor. He wears a simple tunic.

I thought he should probably have a +4 bonus from mage armor no?

Any help with this?

I think the DMs said its +1 for every 4 levels.

It's +1 /4 caster levels now (dodge bonus).

Mind if I ask why?

I believe it's because the system to prevent stacking with Armor AC has not been implemented yet. So it was giving a staggering +4 to characters in full plate. This is a quick remedy to that game imbalancing issue.

Yeah, this is a quick temporary kludge until we can get the real problem fixed.