Auto focusing problem

Question

My Nikon D40 will not auto focus with the quantaray lens...when I bought the lens...they assured me it would be compatible with the d-40...where did I go wrong?Purchased a 420-800mm lense and T adapter for Nikon D40X camera. The lense is for manual use only and does not have a drive motor. On fitting T adapter to lense and then onto camera body, the indictor monitor showed LENSE NOT ATTACHED although i can focus lense, it would not take a picture. It was a nightmare trying to remove T adapter from body