Im using the ALFA'36H and im having troubles wit the handshake.

What happens is if i take the target laptop and put it within 5m of the router i can capture the handshake, but as soon as i go downstairs or make it less line of sight it just doesnt capture the handshake even though im successfully deauthing the target. So im wondering is there somesort of bug with this? because my rt73 device works better then the ALFA when it comes to handshake capture.