LX90 communication with SkySafari 4 Plus for android via SkyBT, problem

I am trying to use SkyBT and SkySafari 4 plus to control my 2002 vintage LX90.  Communication is partially working - skysafari knows where the scope is pointing, but when I try to command the scope to move to a nearby target, skysafari says "invalid coordinates" and the scope does not respond.