How to Use Custom SQL Variables in Network Atlas??

Hello,

I am putting together a new map using Network Atlas to provide at-a-glance information about our WAP (Wireless/WiFi) environment. I am comfortable using Network Atlas and have built a number of maps previously so I'm pretty well-versed in its ups & downs and some of the neat tricks you can pull with it. However, for the life of me, I cannot get a Custom SQL variable to work for some reason.

What I'm trying to do is something like this in a label:

     ${SQL:Select somefield From sometable Where somecondition=${somevariable}}

and it's not working.

Help!!

Thanks!

John