apache fail after subdomain creation

[machinakias]

Hi all...I need your help please...
Here it's my problem:
I set up my domain lets say "mydomain.com",upload the site files,test it,works fine...

Then,i'm going to create a subdomain,like this:
go to user,add subdomain,giving subdomain name like "subdomain" and mount point automatically gives /subdomain

i do not touch anything else...just adding the subdomain name.....

then,i see that it crates the subdomain,but it says "unknown error" in status,and the subdomain is not accesible....

i saw that it does not create any subdomain.db file or directory....
But the MAJOR problem is that after creating the subdomain,apache fails to start! tried to reboot,restart apache etc...no luck!

after this,no site nor panel is accesible,even through the local ip (192.168.1.10....)
No matter what i do,apache does not run....

what i am doing wrong? how can i add a subdomain in easy steps?
could anyone give me some advice?

I use ubuntu 10.04 server and ispCP Omega 1.0.7