Getting Totals Error in RTC Report

I m getting Error when adding purchase line amounts in RDLC layout using Sum(LineAmount)

My Report DataItems are

Purch Header

Integer (Copyloop)


Purch Line

Purch Comments Line

If there is a comment line then it adds same amount extra.

I used some other method ISSERVICETIER function in Purch line OnAfterGetREcord() the line amount can’t summed to any temp variable…

Can Any One Help me pls…