Setting Control Source Property Issue

[Sarah11]

Hi



I am new to Ms access. I am setting the control source property for a text box say txt1. I am trying to display sum of expense amount where bill number is equal to that of bill number displayed on form.
Here is the expression that i used for this.

=DLookUp([SUM("Expense Amount");"tblExpenses";[tblExpenses]![BillNo]=[Forms]![frmExpenses]![txtBillNo])

I am getting Name?# error.

Could you please let me know what is going wrong

Thanks

[CJ_London]

use the dsum function

=DSum("[Expense Amount]","tblExpenses","BillNo=" & [Forms]![frmExpenses]![txtBillNo])

[Sarah11]

use the dsum function

=DSum("[Expense Amount]","tblExpenses","BillNo=" & [Forms]![frmExpenses]![txtBillNo])

Wow!! That worked!

Thank you so much :-) Good day !!