I had a similar problem and searched the forums. I found a useful method that worked for me:
- move you cam on top of the floor in your linden home so you can see it from above.
- try rezz a testprim first (you added and retaken in your inv .. since to add a prim is no problem ) to find a position that works
- if you find a good place just rezz there whatever you like and move it afterwards into the right position
thats it .. sounds funny but it really worked for me .. so it is worth a try.