Render video from timeline only giving me jpeg as option

Still getting used to using the timeline on Photoshop.

To the best of my knowlege i have everything set up correctly. When i play my animation in the timeline it runs perfectly with all items moving correctly. It is only a 6 second animation. Set to 24fps. When i click on render video, it is not giving me the mp4 options at all and only opens up formats just as jpeg, png etc. It doesnt seem to see it as a video. Am I missing something? (Sorry - i'm at learning stage!)