why RB953GS-5HnT tx power can not set to 32dbm？

RouterOS Wireless Networking
1

why RB953GS-5HnT tx power can’t set to 32dbm，It show couldn’t change interface - tx-power too high for card(6), mode is all rates fixed ,it max to 30dbm,
but on routerboard the tx power is 32dbm

http://routerboard.com/RB953GS-5HnT-RP