Date Selection problem In calender

i observe that the webctrl id changes accordingly–>
1. Yesterdays date(28) comes in Fourth (4) Row and Fifth(5)column no .Count starts from 0.
So the webctrl id='celdate_day_4_5
2..Previos months 28 comes in First row(0) and Third(count starts from 0) column (3).so the webctrl id comes in celdate_day_0_3