Crystal Reports Crystal 9 conversion

Message

     Hi,

I am converting Crystal 6.0 to 9.0. In CR 6 for Running Total it uses the function RT. But this function is not allowed in CR 9.0.

Could some one help me how to write this function in 9.0.

My old logic 6.0 is like this:

IF {ram918_r.BREAK_CODE} <> 99 then
RT ("Amount2","Sum",ToNumber ({ram918_r.MKT_VAL}),{ram918_r.RPT_ACCT})

else RT ("Amount2","Sum",(ToNumber ({ram918_r.MKT_VAL})-ToNumber ({ram918_r.MKT_VAL})),{ram918_r.RPT_ACCT})

Thanks
Balaji