[SalesForce] Disallow users to change account record type

I am trying to create a validation rule that should disallow users from changing an account record type with the exception of the system admin.

This is what I have written:

    AND ( NOT($Profile.Name!='System Administrator'), 
    IsChanged(RecordTypeId))

When I remove the NOT, then I cannot change the record type as a system admin, so I added the NOT, but now I can always change the record type. What do I need to change?
Tia, Lily.

Best Answer

You can try this formula in the validation rule

AND(ISCHANGED(RecordTypeId), 
NOT( $Profile.Name = "System Administrator"))

The usage of != inside NOT makes it =, so its throwing error even for System Administrators.

Hope it helps.