Multiple Numbers as String Selectrion?

Hello,
I am trying to create a user prompt so the user can enter multiple numbers.

It works IF the user goes into the Report Select Expert and enters the multiple with the "is one of". But trying to eliminate the user from going into that and instead enter them with a user prompt parameters.

I've set the Parameter for ClubNo as a String type (though it's actually a numeric field)
then a Formula

ToText ({v060ClubOfficersClubAddress.ClubNo},0,"")

Then added this to the Select Expert:

ToText({v060ClubOfficersClubAddress.ClubMbrNo},0,"") IN {?ClubMbrNo} 

However this is not working. Anyone know what's wrong here and how to fix it?

Define not working, please.  Question, is (?ClubNbrNo} set up to "Allow multiple values"?