iPad HTML5 Video element not displaying poster

I'm building an iPad app that loads information dynamically via XML, some of which is displayed in video tags.

The tags themselves work properly and the video can load and play, but for some reason, the iPad doesn't want to render the poster attributes for the videos.

However, once I play any of the videos, all of a sudden all of the p开发者_开发百科osters will show up anytime a video element is displayed.

Anyone else had problems getting video elements to display posters on page load?

Here's how I'm embedding the video:

<video id="videoPlayer" src=" + videoURL + " poster=" + posterURL + " controls="controls" width="480" height="360">&nbsp;</video>

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Might be an unconventional fix, but by loading the poster image somewhere else on the page (that doesn't get displayed to the user) the poster would miraculously show up whenever I loaded my video nodes.