Trying to use a custom proerty in an equation

I have a custom property (\\\$PRP@Plate_Count) in my designtable. I want to use this property in an equation within the samepart as follows:

"Depth@Extrude1" = 0.36 + 0.094 * "PRP@Plate_Count"

I cannot figure out what I'm doing wrong but I know it is with theway I'm calling \\\$PRP@Plate_Count". The Help didn't seem to coverthis situation.

Any clarity would be appreciated.SolidworksGeneral