Niaspan ER and crestor

After my heart attack 1 1/2 years ago, my cardiologist prescribed a statin. This dramatically reduced LDL from 125 to 72 within 2 months. But, after no improvement to the HDL, we switched to Crestor + Niacin. At first, I used a non prescription niacin (Slo-Niacin by Upsher Smith). Over the course of 1 year my HDL increased from 40 to 48. We decided that this improvement was too slow, so we substituted Niaspan ER (2000 mg) 6 months ago.
I was very disappointed to see my new lab report this week with the HDL back down to 42. (LDL continues to be no problem and is now 59.) My Doctor reports that I am her only patient who follows her recommendations including daily cardio exercise of 1 hour, good diet, and following medication regimen who demonstrates reduction of HDL with niaspan. We are going to try for 6 more months.
One theory (of mine) is that I have been taking 1000 mg of Niaspan at breakfast and 1000 mg at dinner, and perhaps, I should take all 2000 before bed. I started taking niaspan at meal routine to reduce side effects, and have had very little flushing. But, I will now try to take all 2000 mg at bedtime after a small snack and 1/2 hr after the aspirin. I'll report again after my next lab report, but am curious to know if anyone else has these disappointing results.