Tremolo between notes

I would just like to ask if putting a tremolo/tremolo/roll between notes works properly, because I have found that (on the piano at least) putting a double-line (semiquaver) roll between two notes only plays them for half the duration I think they are supposed to last (i.e. dotted minim = dotted minim (where = is the tremolo) plays the tremolo for the duration of half a dotted minim and plays the last dotted minim for the other half of the duration (or at least that's what I think is happening). Also an unmeasured roll (three lines) between notes doesn't play, which I assume is because you don't have recordings of tremolos like this rather than it being a bug.
Just thought I'd mention it
Just thought I'd mention it
