Help facing Prblem with Date and Time in my CCTC DVR

[viswa567]

Dear guys
i have a 8 port DVR in that i am facing problem with Date and time every day date automatically changing even tough i am corrected it next day again changing
Ex: today 16/3/15 my system but in my dvr its appearing as 17/3/15 i changed it a s 16/3/15 and date also corrected. Next day after 12pm generally 17th has to come but my DVR taking 18th if i not corrected date next day it is taking 20th date

what might be the problem kindly suggest because of this problem CCTV data also not saving properly kindly help me out

Thanks
Vinay