Adding to project after complete

[Anonymous]

So I've made the design from sketch, I revolved and made into a full modeled object and eventually made into an stl.  Now I wanna go back and add/change to the design but when I try to I end up "drawing in the air" like it wont attach onto it.  Not sure what I am doing wrong and it's really frustrating. Please any help will be appreciated.  If you need screen caps I can post later today.

[laughingcreek]

yes, a screen cast and a file (file/export to .f3d, attach to post)