Do I have to link grounds on switches?

There are (4) "outer rails" of a given turnout. Is your layout wired for common ground? What turnouts are you using? How do the trains run through them... OK?

My layout is wired for common ground, if going around the loop, the most outer rail is the common.  I have nearly exclusively O-42 Ross & Ross ready switches.  On one that is giving me fits, it just goes to a small siding, but the siding won't power a loco--if I place my loco on it, my remote tells me there is no engine on the track. However, if I just run my loco over the straight portion, no trouble. On the other, it is connected to a string of switches as it goes into my "engine yard."  Oddly, if I bring my engine past the offending switch and put it on a piece of rail meant for parking, it fires up, but if I try to run it out of the yard, as soon as it hits the switch, it powers off.

All of the running rails you do not want isolated for non-derailing simply have to be powered by jumpers to layout common ground.