[Elecraft] K2/100 Problem with Hi Reflected Power driving amp

[John]

Hi all. I have a K2 with the KPA100 installed. I'm using the K2/100 to drive
a tube amplifier through a tuner. The K2-100 keeps tripping off with the
HiRefl message showing not every time, but often enough that a QSO is
impossible. The K2/100 doesn't 'reset' (has no output) when rekeyed unless I
rotate the power setting knob ever so slightly. 

What am I doing wrong? Any way to increase the delay before the High
Reflected power takes effect as I suspect it's transient? I also have the 
t-r rel

Any assistance will be greatly appreciated.
73, John  WA6YSY