Ok, looks good...
First with some basics...
Ensure all your variables are explicitlly declared/dimensioned. Then compile it. It should give you a good idea if the compiler is unsure about the variables.
Now for the reason I think it fails. Try this.
....
Dim msg As string
msg = "INSERT INTO TblOver50 (Nostro, Ledger, CurrencyType, Day, CredDeb, Total) VALUES (Bank, L60, CurrType, J05Date, DebCred, USDTotal);"
debug.Print msg
...
The output will be this...
"INSERT INTO TblOver50 (Nostro, Ledger, CurrencyType, Day, CredDeb, Total) VALUES (Bank, L60, CurrType, J05Date, DebCred, USDTotal);"
Why you ask? You have actually incorporated the variable into the SQL string. Instead try...
DoCmd.RunSQL "INSERT INTO TblOver50 (Nostro, Ledger, CurrencyType, Day, CredDeb, Total) VALUES (" & Bank & "," & L60 & "," & CurrType & "," & J05Date & "," & DebCred & "," & USDTotal & "

;"
Building SQL strings is the pits sometimes aint it.
Best of luck Joanie.