Software Resource rule to check value data of a "(Default)" registry value

I have a Software Resource that I would like to set a detection rule base on a registry key. The registry value that I want to check is one with the value name (Default) which is a blank name but has string value. The rules screen in SMP does not seem to handle empty registry value names. It gives an error saying it cannot be empty. Entering "(Default)" without the quotes does not equal the empty value name. The screenshot below shows the properties of (Default).

I tested the detection rule to check the data in the "test" registry value and it is able to detect the value. However, I need to be able to specify an empty "Registry entry" field in the detection rule expressions screen.