Gardening and Horticulture - Lilac Bush is not doing very hot

We moved a large lilac bush about 2 years ago when we built a new garage and ever since it has not been doing too good. Actually, we have not seen flowers since we moved it, there are very few leaves closer to the top of the branches and even those are not full size. Take a look at the picture http://s189.photobucket.com/albums/z166/sergv_photo/?action=view&current=P1010030.jpg. Is there anything we can do to try to bring it back? We have been watering it quite a bit, but there is still nothing. I was thinking about cutting it back quite a bit, but don't want to cut off the only areas with the leaves.

Was informed that the image did not work...so here is a new one
http://i189.photobucket.com/albums/z166/sergv_photo/P1010030.jpg

How's the soil? Unsure, have a soil test done. How much sun does the plant receive each day?

I believe the soil is good-there is a similar bush growing just on the other side of the fence. Gets sun pretty much the entire day

I had the exact same problem with mine, and I did cut it all the way down. I felt like crying afterwards, but it grew back nice and full with lots of lilacs. You hate to do it, but sometimes it's necessary.

Any suggestions on how far down I should cut it? Is there certain time of the year I should do that?

I just cut mine all the way down and I cut it after the flowers were done. It started new growth before the fall. I don't know if that's the right time to do it, but I find the lilac bush to be very hardy. It just kept coming back better no matter what I did or when.