please help me with dragon

i have trouble with my dragon reciever ,it can not show me all the channel of hot bird is the tuner very week or there is some setting i can do it.and some times after i see art the channel desapear and the massage coming to me when i try to use the manual scan to get hot bird channel like 12360 tell me that THE TUNER HAS NOT LOCKED can you help me please so i can see all the hot bird channel however when i use SKY reciver on the same cabil it bring all the channel.so, please what is the trouble is the dragon tuner is week or there is some setting i have to do it.