Why doesn't library feature work?

Pro/E has a similiar feature to SolidWorks' Library Feature part, and I'm guessing they don't work the same.  I've created what I thought would be a library feature part, however - I can't seem to get this thing to work at all - I'm guessing this doesn't work like Pro/E's User Defined Features.  I'm really hoping I've gone it about completely wrong.  I was hoping to use this feature over and over in either assemblies or parts within assemblies.  The important part for me is the configurations and their attached display states.

So here's how I was hoping it would work:  I would create sketches in a "Frame" assembly.  For each part, I could insert a "start part" containing all the reference points/planes etc needed for my feature, but based on mates, would be sized to the correct length.  But, every time I try, I get an error saying can't be created... something something...

I've attached the parts I'm playing with - can anybody tell me what I'm doing wrong?

Thanks for any help,

Todd

SolidworksParts And Features