if you will give * (then you have to put all value in in field(dummy)) because * means -only that data which is available in section access field.
if you will give
CALENDAR YEAR,CALENDAR MONTH
now you will use * means only u can see 2,3
if you leave it blank then you will see all data available in field.
The problem is that it's not understanding you want a relationship between year and month, so it's simply restricting month to the value you dictate unless it knows there are other values available.
The best way I can think to do this is to create a group or flag in your script. Attach this in your model to your date field, and then in your section access restrict on the group.
For (a rough) example:
If(Year=2011 and Month=3, 1, 0)) as GROUP
Then in your section access, use GROUP as your restrict field and 1 as the value to restrict on.