Using Excel Built-in Functions on top of the UDF

Question

I don\'t know why for some reason the Excel built-in function =SUM() can\'t really sum up the results created by the custom UDF. It appears to always end up with 0.

Answer 1

Is your UDF returning a number or a string that happens to contain numeric characters?

If I go into Excel and type in '10 (10, formatted as a string) and '15 (15, formatted as a string), and SUM() them, I get 0.

If I type 10 and 15 (formatted as numbers) and SUM() them, I get 25.

Some example code that reproduces the problem would allow us to answer for sure.