Problem triggering workflows

I want a field that has a client's full name in all caps. I collect the fist, middle and last name and I want a workflow that combines it all for me and makes it all caps.

I set a workflow that should trigger whenever the First Name, Middle Name(s) or Last Name fields are edited. Here is the custom function that I use:

void Untitled_Function (string FN, string MN, string LN, int Contact_ID ) Edit Arguments

Name = input.FN + " " + input.MN + " " + input.LN ;

Info Name;

UpperName = Name.toUpperCase() ;

Info UpperName;

RecordUpdate = zoho.crm.updateRecord("Contacts" ,input.Contact_ID.toString() ,{ "Client_FLN_All_Caps" : Name } ) ;

Info RecordUpdate;

It looks like everything is right but nothing happens when I edit the fields. Is there a way to trigger the updateRecord that I am missing?