[Elecraft] k3 doesn't toggle power level with kpa500

[Rob May]

I recently had to take my K3 out of service while I waited for a new K3SYN board.  Now that it is all back together the power level on the K3 will not toggle when the KPA500 is switched from standby to operate.  "Operate" and "Standby" appear on the K3 LCD screen but the power level doesn't change when I switch the amp in.  Everything is hooked up the way it's been for the past three years, only the K3AUX cable, power and RF in/out are connected on the KPA500.  

KPA500 s/n 112  FW 1.33
K3 s/n 1417 FW 4.67

I know I'm just missing something simple.  Thanks.
73,
Rob
NV5E