Getting the prev record value

[Afrosheen via AccessMonster.com]

Good morning and thanks for reading this.
On my form I have a sub form. In that sub form I have 4 fields I'm using.
PrevBal Earned, Used, and Bal.
When I do the calculations on the current record every thing comes out
correct. Where I'm having the problem is when I go off that record and go
back in at some point in time I can not calculate off the previous record
balance.

I've tried this code and it doesn't work: =GetPreviousValue([frmfurlough3],
"bal")

I'm trying to calculate like this:
bal = PrevBal + earned - Used

In this statement the PrevBal is from the previous record.

What I need to do is to get either the Bal or the PrevBal so my calculations
come out correct. All fields are number fields.

Thanks for your help.

 

[Afrosheen via AccessMonster.com]

Sorry, What I failed to mention was that I set up a text box with the control
set to

=GetPreviousValue([frmfurlough3],"bal")

Good morning and thanks for reading this.
On my form I have a sub form. In that sub form I have 4 fields I'm using.
PrevBal Earned, Used, and Bal.
When I do the calculations on the current record every thing comes out
correct. Where I'm having the problem is when I go off that record and go
back in at some point in time I can not calculate off the previous record
balance.

I've tried this code and it doesn't work: =GetPreviousValue([frmfurlough3],
"bal")

I'm trying to calculate like this:
bal = PrevBal + earned - Used

In this statement the PrevBal is from the previous record.

What I need to do is to get either the Bal or the PrevBal so my calculations
come out correct. All fields are number fields.

Thanks for your help.