High Tx but low Rx rate, with good signal and CCQ, WHY?

Hi, one my client have signal on 802.11g: -52, signal to noise: 46dB, Tx/Rx CCQ: 100/0 (why also here zero?). Pings are max 10ms. There is just one another network here and, this client have signal on that network: 10dB.
Tx/Rx rate in wirelless table is: 54/11.
Please can you explain me why it like this and where can be problem and how to solve it. Thanx.

If your client doesn’t use Mikrotik based equipment, RX quality can’t be meassured, so that’s why it is always 0.