First, Apple stopped supporting and developing H.264 in a QuickTime container. You don't want to do that. Second, the output module in the Render Cue is not capable of multi pass rendering and all MPEG encoding benefits from MP rendering. Third, the ability to render a very clean mp4 using H.264 compression is included in the Adobe Media Encoder along with some really good presets for common delivery standards.
All of this information in available in the Help files and is posted all over this forum and the net in general.
If the Adobe Media Encoder does not solve your problem then get back to us. If every rendering option gives you a black screen then you have other problems with your comp and we need workflow details.
alright, media encoder seems to have solved my problem!
MyHelp files freeze up and when I google, one of the first links is to come here.
"All of this information in available in the Help files and is posted all over this forum and the net in general."
Why not add some actual help or just say nothing. Makes it look like you'ld rather not help.
What is a forum supposed to be for anyway, to scorn people who come come for help. Maybe they have beenlooking but been unlucky... land here and get told this...
here's the Adobe help file about rendering: Basics of rendering and exporting in After Effects CC
if you want to have an option to render H.264 under Quicktime, you need to have Quicktime installed. but be aware that this specific codec under quicktime is giving poor results in quality and size. you are better off rendering your composition thorough Adobe Media Encoder by adding the composition to the render queue and click "Queue in AME" (in CC2017 and later) or Composition->Add to AME (all versions - but this is the second best choice).
if you insist on having a decent mp4 option right in After Effects, you should consider this plugin: AfterCodecs - aescripts + aeplugins - aescripts.com