SEWIO open sniffer miss response

[eyalkatz1996]

Hii
I'm running zbstumbler using SEWIO open sniffer with NEST hub.
I'm expecting to get a response every time the broadcast is sent at the NEST channel.
In fact, I do not get NEST response consistently. to try and debug the problem, I'm using 2 devices: one of them with the stumbler and the second listing on the NEST channel. I found that the NEST hub response every time but the stumbler miss the response.
It looks like the beacon request time response is smaller than the open sniffer switching time from Tx(sending the broadcast) and Rx (getting response )
I can't use another device.

What should i try to get a more consistent behaviour?
Thanks!