From the “Subtitles set too close” in the error message, it sounds like the program is complaining that you have one more more sets of subtitles whose on/off timecodes overlap. Take a look at the timecode for line 236 in your script and check the timecodes of the lines before and after it. It might be complaining that the OFF time of line 235 is the same as the ON time of line 236 (or 236/237’s). I’ve heard of lower-end programs throwing fits if there isn’t a gap of a few frames between the titles.