Adding a dimension from edge to circle

Somewhat new to solidworks -- but I can't figure out why this isn't working! Hasn't been a problem before. I have tried removing all previous relations, keeping it as simple as possible...

I want to specify the distance from the edge of the square to the cylinder, say 30 mm. I have attached a dummy sample.

It seems so simple, but I must be missing something...I appreciate your help!

SolidworksParts And Features