you have to be close to the surface you right click onyou can crouch and set your bipod down on the ground in front of you, or stand/sit next to a table (approx 3x high brick)
are you looking at the surface and right clicking? you have to look where you want the bipod to be deployed in order to deploy iteg: look at top of table, right click until its deployed and you cant move, then you're in bipod mode