Runtime Error 1004 when replacing formula

Question

I am using the following code to add something to a Formula in VBA (for debugging purposes I am using the variable currentFormula, instead of doing it directly):

Answer 1

CStr formats the number according to the current system locale.
Formula accepts formulas in English.

The function that converts numbers to strings in an invariant way is Str. Note that it prepends a space to positive numbers which you might want to remove:

currentFormula = currentFormula & "+" & LTrim$(Str$(difference))