Dlookup

you may break down your function into 2 parts...

first using your first part of function and see what was being returned?

=DLookUp("Amount_ Aggregate","tblDraws","ID=" & [DrawIDrpmt])

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similarly, do the same for the 2nd function:

=DLookUp("Amount","tblDraws_Details1","DrawIDrpmt=" & [ DrawIDrpmt]) 

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this will give you clue which part is getting an error and let you handle that error more efficiently.

I imagine its a paren

Or missing Operator?

The first argument in DLookup is an expression where vba checks for missing operators.

DLookup ("x + 2", ...: Expression to look for value of field x + 2.

In what Rayan assumed, your code assumes, because of a space in the name,  a missing operator between assumed fields: "Amount_" and "Aggregate".

That was it.  Thank you