You're not doing anything wrong, Apple is. iOS devices do not play nice with non-Apple devices, so you won't be able to pair a Samsung phone to an iPad with stock options. You'll need to either jailbreak your iPad and do some hackery or use 3rd party file-transfer tools.
You can only pair 'accessory-type' Bluetooth devices to your iPad like speakers or headsets, but you cannot transfer files to another non-iOS device via Bluetooth.