How about this, IMHO:
Dim str As String
Dim n As Variant
Dim FD As Date, TD As Date
FD = Forms![Report Menu].FromDate.Value
TD = Forms![Report Menu].ToDate.Value
str = "[RemitDate] >= FD AND [RemitDate] <= TD"
n = DSum("[GSTPaid]", "queryJobRemittance", str)
...
Haven't tried it...