Arch Linux doesn't mount two USB drive?

One is USB modem which is connected and working and problematic one is a plain vfat USB stick which contain data ....that is the fellow not mounting :(

I have tried to see it by fdisk ....it doesn't mount autometically...

Is there any UDEV rule for that?? Because I have put a udev rule to remove the usb-storage thing( I had to.. otherwise the usb modem wont get connected... it waits for storage to relase the port)

Any idea and solution would be greatly appreciated

PS: I am running Arch distribution.

Thanks