Recently, I found the 30mg. Adderall IR I was prescribed to be totally ineffective. I've seen posted about this from a couple of years ago and it is important to note that it it still a problem.
I would see your doctor about this problem. Maybe you have natural tolerance to amphetamines or perhaps you would have better results with a different class of medication.
Methylphenidate (Ritalin) may be more effective for you.
Do you notice any effects at all from your medication?