Thanks Steve for your reply ,

when connected to ground the deviation is about 02H.
Also if all the channels are connected to gnd. simultaneously,
& calibration is done w.r.t. channel zero, the readings in the channels are not equal.
But at the same time they donot differ vastly.
The differnce between max-min of all the channel reading when connected to gnd. is about 05H.

Mak.