User API point always gives me "user not found" if the username is just the numeric value. It works well if the username is alphanumeric - 2132132abc
curl -H "Rest-User-Token:**********" -H "Rest-Method: PUT" -d "" -X POST https://community.my.com/api.ashx/v2/users/2132132.xml
Any idea what could be causing the issue?
Any help would be greatly appreciated.