Vegas 12 help!! Sony AVCHD MP4 format greyed out

[MasonN]

I've just edited my first video in Vegas 12, the clips were recorded in 1080p, I do have the original audio plus music (don't know if any of this matters), I'm trying to render it at 1080p in Sony AVCHD as an MP4 at 60 frames per second for the best quality, however when I customize the template everything is fine other than the fact that when I click the system tab and try to change the format from m2t to mp4, I don't have the option. It's greyed out and I can't even interact with the drop box.

Right now I'm rendering it in MainConcept AVC at 1080p, though when using this method I can only render at 30 fps. I was excited that I have the means to record at 1080p and am aiming to render with the best possible quality. From the research I've done, for posting videos on the web the Sony templates are the way to go and provide the best quality.



Can anyone tell me what I could possibly do to enable the mp4 format within Sony's template? I've tried everything and have researched the web for countless hours for a solution... I feel like it's probably an easy fix, but my lack of experience in this program is a bit of a set back. Help is MUCH appreciated!!!

 

[kenrivers]

Were the original clips recorded at 60 fps? If not, that could be part of the problem. I use Premiere Pro and just to see if I could export a clip shot at 30 (29.97) fps as a 60 fps (59.94) fps clip. I checked the export options. When I tried to export the file as H.264 at 59.94 fps I got an error (warning) message "Invalid framesize/framerate..." Unless the original footage was shot at 60 fps I don't see how exporting at that frame rate will increase the quality of the video, but I could be wrong.