Sub total of a field in report

[djwasim]

Hello All

I am facing some problem in subtotal of a field called rate in which i am using this formulla

=DAvg("[Rate]","Main Query","[TranDate]<=[Reports]![Issue Plot/w]![Trandate] AND [Rate]>0 and [Itemdes] = '" & [Itemdes] & "'")

but when i use to sum this field the result is "0"

Plz help me if you can

 

[Mattster]

that function seems a bit odd. I am confused a little about
and [Itemdes] = '" & [Itemdes] & "'

Unsure what this is doing. if you remove this section do you get the result you are going for. this statement to me, and I am not the best, is saying
get ?? apend it to [Itemdes] apend all this to ??

If you take out the & & it might work a little better. all I can say though is that last line is extemely odd to me