I'm testing out my bindings for the F-16.  I notice that once I'm in the cockpit with engine running if I unlock the spider I can relock it, unless I open the canopy.  Then after closing the canopy the spider won't relock, the cockpit eyebrow light stays lit and WARN flashes in the HUD.  I can fly the mission fine.  Is this something I just shouldn't be doing (opening and closing cockpit after engine start) or what.  I searched the F-16 forum and found nothing on this particular issue.  Happens on the Instant Action: Ready on Ramp, and Takeoff missions.  Thanks.