Actually, all the channels were there. I just moved some of the channels from one location (channel number) to another. After that, when I turned my receiver off and then on, Asiasat 3s channels disappeared. I tried my level best but all in vain.... I am not that much technical. In case of NileSat and Hotbird, signal strength is about 70% and channels are there but in case of Asiasat... there is no signal with following settings.
My receiver settings for Asiasat are:
Diseqc position "D"
Whereas for Nilesat and Hotbird settings are:
Diseqc position: "B"