I'm using a single-unit CIVA INS on my CS 707, and when I try to do a DME update, it will not work. Here are the steps I take:

Tune NAV radios to the VOR/DME
Select WAY PT on my INS
Right-click 7 and 9
Enter the coordinates of the VOR
Hit INSERT
Right-click 3 and 9
Attempt to enter the elevation of the VOR

...But it won't let me. And when I try WYPT CHG/(number)/INSERT, the flashing 0 does not go away.

What am I doing wrong? I hate having the INS turn me off-course because it hasn't been updated :(  >:(