HD recording is not working while shown another channel

[Minesh]

i buy airtel HD recorder stb 2 months ago by paying 5k for 12 month subscription . At that time i can recording 2 channel while shown another..but few days ago i cant do that..Now i can record a channel only when i shown that channel..when i change the channel recording is automatically stop..only 2 notification is shown1- ok to conti. show channel2- exit to stop highlighted program.