Play only frames with markers

Hi,
I copied this expression from Mark Christiansen's AE CS5 Studio Techniques.

I'm working on video footage in CS5.5 and the code doesn't work properly. I have applied several markers to the video layer with Time Remapping added. The expression plays the first marker on the first frame and the last marker on the second frame. Everything else after is frozen on this frame. I cant work this one out. Does anyone else have this problem? Can anyone help me fix this issue?
Thanks in advance!

n = marker.numKeys;
if (n > 0){
f = timeToFrames (time);
idx = Math.min (f +1, n);
marker.key(idx).time
}else{
value
}