query subsutution

[vennai]

I am using the following query in my report.

Select :pr_sub,sum(custom_money1)
from pr_customers
where (all the conditions)
group by :pr_sub.


so in the after parameter trigger,i subsuitied the value for :pr_sub.

The problem is in the result,for ex if :p_sub = 'custom_number',
then the result is displayed as

custom_number 4
custom_number 5
custom_number 6


Instead of the orgingal row value,i am getting the above answer.please let me know how to solve it.