Hi Art--
I'm assuming you have made the connections between the TS590S and the AL811h per the pic on page 68 of the 590's manual. Did you remember to switch ON the amplifier control relay via Menu No. 53 (for HF)? If you have the internal relay ON, you then need to select 2 or 3 to set your TX relay delay time, 10ms or 25 ms respectively. See page 53
While I don't own a 590, that is the info I found in the manual. If I have things messed up, I'm sure someone will jump in and straighten us out

73 & GL
Frank, W1NK