Not Displaying a field in 2009 report

Hi All,

I have a table LedgerJournalTrans , in this table three fields are there AccountNum ,AmountCurCredit and AmountCurDebit . In my report I have taken one additional  field which is "Balance". in this Balance field i want the substraction of AmountCurDebit and AmountCurCredit and also grouping of AccountNum.

I tried many ways by writing display(),Fetch(),Modifiedfield() and taken a tmp table also for balance field..but no use it is showing 0.0  0.0 as Report output.  I dont know how can I get the data in to balance field in my report and and accountNum grouping also.

    Can any one suggest me  syntax and which methods will write for this issue.

Thanks in Advance

Pallavi