Unhappy [Q] can't enter into download mode but into recovery

I installed custom ROM called acecream 1.4 from this thread...
http://forum.xda-developers.com/show....php?t=1925850

then my mobile s5830i kernel became rafeaul baugiss kernel but that custom ROM worked perfectly..
But when i tried to use dwnload mode in reboot, but it just reboot again without entering download mode..
then i came to realize that problem..

amyone please help me to enter download mode, because i want to install back my original firmware...
Odin is prescribed by many thread to flash back to original firmware..
but for odin, i need to enter into download mode

but my mobile can enter into clockmod recovery without anyissues...

can i install original samsung firmware from recovery mode without entering download mode????