Can anybody help! i am at the part where you go down through the trap door and there is a guard patrolling the passage way but when you take him out another guard appears but get's called away you then after follow him and use your thermal imaging to key in the key code but i can't seem to do it does anybody have the key code. Thanks

I think this is where you are, try this

In the hallway, shoot out the 2 lights closest to the keypad and door. Then open the last door on the right. Turn back around, 2 guys will be coming to use the door. Wait in the shadows. There are several approaches here, you can take both of them out with sticky cams quickly, or cam the last guy through the door, or let both through the door and sneak in behind them. If you cam them both, make sure to use the thermal goggles to see which numbers they pressed. An orange color will indicate that key was touched most recently and a bluish key will indicate the first key touched with varying shades in between. To help yourself out, when you are looking at the keypad with your thermals on, press and hold the black button.

Read the first tread in this forum for more help