OK, here's the official answer. The question is "Why can't the Hubble take a picture of the lander?"
"Any mirror has a smallest angular size that it can resolve. For the Hubble scope, that resolution is about .014 arc seconds in the ultra-violet (larger in the visible range). This, by the way, is a theoretical limit. The distance to the moon is about 240,000 miles. At this distance, the smallest thing that the Hubble could see would be about 86 feet across."