[Elecraft] K3 Squelch problem

[aa1o]

Hi,
I am having a problem adjusting the squelch.
I made a 6 meter fm repeater contact this morning, but the other station was 
breaking up (he said my audio was fine). I thought the squelch threshold 
must be set too high. In trying to set that value in the config menu I 
get -- for a value and cannot seem to change it. How do I enable the squelch 
control?
-Bill AA1O  K3 287