Doug, I think you'll find this aircraft does not use the standard animation for landing gear. SAMM's front-panel checkboxes assume standard animations. Use of non-standard animations in payware aircraft is not unusual since they often have capabilities beyond stock aircraft.
But, that doesn't mean SAMM can't handle this aircraft - only that SAMM needs a little help from you.
What you'll have to do is open the Listings and Tools menu, explore the parameters of the aircraft to discover what animations are involved in the undercarriage and set those parameters accordingly. The manual contains a section on the use of this dialog. Of course, this means that you must have (or a desire to acquire) some knowledge of aircraft design techniques. If not, I suggest you find another 777 for static use.
Don