Still not able to connect

HI Guys,
I am using Samsung Galaxy SII EPIC 4G.I had done the same as mentioned above and was able to transfer files for just one time. Now wenever I connect the phone to laptop, it shows only camera reader. It doesn't shows the mass storage options with drive names.
Wenever, I click on the "Connect USB storage" after attaching the cable, it shows that "USB is coonected, Remove the cable"
Pls help how could I easily connect the phone to the laptop using usb cable