communication of two b200 via ax.25

Hi,

   I have this flowgraph programmed in two b200 SDRs. I want to communicate via ax.25. The problem is both are not consistent in receiving data from each other. It is like for every 10  transmitted data, around 5 are received from the other end. Can anybody tell me what I did wrong so that the two SDRs will communicate consistently? Note that both of them are just located very near to each other? Here is my flowgraph:

RX:

TX:

Regards,

Bryan