Hi,
Do one more trick.
Create all external nameservers dns*.bigrock.in in KloxoMr control Panel as mentioned under the category Parent in:
http://www.intodns.com/desimoron.comChange in the General Settings SOA and make dns4.bigrock.in and Primary Nameserver.
Request incero.com to add a subdomain webmail.desimoron.com with the Ip address off your server.
Wait for a few hours until the Zonefiles gets updated. Then lets see if your webmail connection works.
I suspect that there are two Nameservers, namely dns4.bigrock.in and ns1.desimoron.com, both claiming to be SOA Primary Namesevers.
In this case, your webmail.desimoron.com tries to connect with dns4.bigrock.in but cannot find any information on the Ip Address of webmail.desimoron.com.
Thus, there is a connection error.