Video not playing on iPad using HTML5

I have following HTML code that is working fine for window PC and iPhone 4 with iOS version 7.1.2.

<video id="v1" width="640" height="480" controls>
<source scr="/videos/test.mp4"/>
</video>

but when I try to play this on my iPad 2, it does not play. iPad has version 8.2. it shows play button in the center with cross on it. then I try same file with .3gp, .ogv, .webm formats. the cross sign disappeared but video is still not playing.