Did you copy/paste the formula exactly how you have it on the form?

If so, it looks like you may have a stray comma before the closing parentheses

=SUM(V__Banked_not_Booked_Checks, V__Banked_not_Booked_Checks_1, V__Banked_not_Booked_Outgoing_Wires, V__Banked_not_Booked_Outgoing_Wires_1,))

And an extra ) at the very end

SUM(INDEX(Adjustments.V_____Adjustments_1, ROW())))

However, you have the INDEX function inside of the second SUM function. Is this supposed to be a sum that occurs on each row inside a table?

If this formula is outside of a table in a standalone field, the problem may be that there is no "ROW()" value to reference in which case it should probably just be the following:

=SUM(V__Banked_not_Booked_Checks, V__Banked_not_Booked_Checks_1, V__Banked_not_Booked_Outgoing_Wires, V__Banked_not_Booked_Outgoing_Wires_1)) - SUM(Adjustments.V_____Adjustments_1)

SUM and INDEX really don't need to be combined unless you have multiple variables involved because using INDEX tells the formula to grab a single row/value meaning there would only be 1 value in your SUM rendering it unnecessary.

If the goal is to SUM an entire column, then you wouldn't want INDEX because the SUM would already recognize the variable as a collection and add all the values together.