I may be missing something, but I don't see equations in my custom library part.

I have a feature, a tooth, that is defined by the radius of a cylindrical component. I had this configured nicely with an equation. I would like to use this feature all the time and don't want to redo all of the reference geometry etc. every time, so I made a library feature. All of my references are in place, but the equations disappeared. The feature is worthless without the equation and the ability to modify the parameters for each new part that I create. Is there a work around for this? Why have the equations disappeared in the first place?