<video> works in the iPad, but not on the iPhone

I'm trying to embed an M4V video, it works on the iPad but not the iPhone. On the iPhone I get a play button crossed over (the can't play button).

I am testing this on iPhone 3.0 (Original iPhone).

Any help/advice would be great.

My code:

<video id="sr-video" pos开发者_StackOverflow中文版ter=''    controls="">

<source  src='http://blip.tv/file/get/FILE.m4v' type="video/m4v"  />

</video> 

Update:

I've added a mime type like so:

video/mp4 mp4 m4v mp4v mpg4

Did not help...

What are the video/audio codecs and resolution of the video you are trying to play? I would check that the format of the video is supported by the original iPhone, see: http://reviews.cnet.com/8301-19512_7-10114945-233.html

For instance, unlike the iPad and the latest iPhone, previous iPhone models were not capable of playing 720p video.