Could you tell me if I use a compressor in a bus and while using the bus from any one instrument track, it does not allow me to pan hard right or left, I mean if I pan hard right or left it remains on other side atleast 30 to 40%. How can I solve this problem - I tried many ways. Thanks

Generally, compressor should be use as insert effect. When you use them on a bus, you are still getting the signal on your original track as well. You could always pan your track and your bus and it will work... Just make sure that you really want to use the compressor on the bus and not as an insert because that way, you are getting an uncompressed signal and a compressed one at the same time.