Average of count of column in Pivot

[kd]

Hi,

I need to calculate the average of a column in a pivot for eg. Jan 09 and
Feb 09 so on and so forth for the whole year. Now how can i calculate the
average of count of Jan 09 and Feb 09 ie. (Jan 09 + Feb 09)/2 . Data in the
column just says Jan 09, feb 09 , mar 09 so I have to take their count
against other columns and then take its average.

I tried calculating item in the pivot but its giving error "Calculated items
do not work with customs subtotal".

If you can advise the above or its alternative, I'll be greatful.

Regards,
KD