changing frame rates within print to file

[mattie]

Anyone know why a 1280x720p50 project can't be 'converted' within the print to file area to a 1280x720p25 file?

I can 'print' the project with 'conversion' to 1280x720p 24.75/30 fps but not 25 which one would think would be the most acceptable for a 50p project!

any ideas please let me know.