sum function in query layout

[div_1234]

hi
i am using query layout ,its t supporting sum function,what is the alternate function available in cognos.


total([Query1].[Current] * _months_between('09/30/2010',[Query1].[acc] - 0.5))/[Query1].[Current]/12

it gives me error like function is not recognize at position '5'

Any help?

[blom0344]

_months_between('09/30/2010',[Query1].[acc] - 0.5)

This would require 2 true dates. I wonder whether subtracting 0.5 is allowed here?