Cmd shell proxy

I am attempting to execute xp_cmdshell with a non-sysadmin db login. I have created a Windows account and the associated proxy account in SQL Server. I have verified SQL Server is showing the proxy account credentials. I am still getting the following error. What am I missing? Guidance is very appreciated.

Microsoft OLE DB Provider for SQL Server error '80040e09'

EXECUTE permission denied on object 'xp_cmdshell', database 'mssqlsystemresource', schema 'sys'.

Try granting execute permission on xp_cmdshell to the non-sysadmin login

use master;

GRANT EXECUTE on xp_cmdshell to [non-sysadmin_login]