Just ran this - it came up with an Error message saying there maybe a Marker at this position - nope . . Tried a fresh download from the SUndance site . . nope . . same error. Any ideas?
If you get that error message, there is already a marker at a position where the script is wanting to add a new marker. You might try simply deleting ALL markers and then letting the script add the markers as you need.
That particular script does not check for existing markers before attempting to add the new marker.
Also be sure that you are specifying the interval in the SAME format as the Timeline Ruler! If the timeline ruler is set to seconds or absolute frames and you enter 00:00:10;00 as the interval (i.e, SMPTE), Vegas will interpret this as zero (0) and try to drop markers at zero intervals (which will fail after the first marker is dropped at zero)