There are at least a few possibilities for why rendering might fail:
It could be because you have a space in the full path file name. That includes the file name you choose in start-movie or render, but also the folder that your NLOGO file is saved in, or any folder that is saved in, going all the way up. In this case, the solution is generlaly to rename the file/folder so that it no longer has any spaces in it.
It could be because you are using a shape that is not supported by raytracing.
It could be that it can't find one of the images that you're using for a background in raytracing, or wrapping around an object. Did you misspell the image's file name? (Remember to include the file extension -- .JPG or .PNG, etc.)
NetLogo probably still created a POV file (but not a PNG file, since it failed to render), and you might try opening the POV file up separately inside the POV-Ray program, and try rendering it there, and then read the error message. If you copy/paste the error message into a Q&A question, we might be able to better figure out exactly what is going wrong...