CFS2 add-on planes waypoints problem...

Im trying to make a mission in CFS2's Mission Builder using Add-On jets as the default aircraft.
However, the AI jets dont want to follow their waypoints like the stock props do - they just fly round the mission area in a wide circle doing nothing!
I've checked my wapoint commands dont say to 'loop' or 'loiter' and tried moving waypoints but it doesn't help.
I was wondering if anyone out there has had the same problem and knows what to do to fix it.
Any ideas would be really great!
Thanks!
Ed
However, the AI jets dont want to follow their waypoints like the stock props do - they just fly round the mission area in a wide circle doing nothing!
I've checked my wapoint commands dont say to 'loop' or 'loiter' and tried moving waypoints but it doesn't help.
I was wondering if anyone out there has had the same problem and knows what to do to fix it.
Any ideas would be really great!
Thanks!
Ed