UDF problem

Hi,

I created an add-in file with a few functions and I activated it.

*** All my functions begin with "udf_" ***

1) If I go to tab Formulas > Insert Functions -> User defined, I can see them and use them.

If I begin to put the begining of the function name in a cell "=udf" why can I see the list of the functions that begin with "udf"?

I tried to put =udf_age("01/01/2000") ant it works.

Regards,
Elio