How do I fix a "Parser Mismatched Metadata" error from the Facebook Open Graph debug tool?

Question

I'm getting an error from the Facebook Object Debugger for a web page I recently added Open Graph tags to:

The parser's result for this metadata did not match the input metadata. Likely, this was caused by the data being ordered in an unexpected way, multiple values being given for a property only expecting a single value, or property values for a given property being mismatched. Here are the input property =>content pairs that were not seen in the parsed result: 'article:published_time => 2012-05-15'

Here are the meta tags the tool reports:

Meta Tag:   <meta property="og:site_name" content="Mysite.com" />
Meta Tag:   <meta property="og:url" content="ful url" />
Meta Tag:   <meta property="fb:app_id" content="a number" />
Meta Tag:   <meta property="article:published_time" content="2012-05-15" />
Meta Tag:   <meta property="article:author" content="url to user profile page" />
Meta Tag:   <meta property="og:image" content="url to png" />
Meta Tag:   <meta property="og:type" content="article" />
Meta Tag:   <meta property="og:title" content="Well Versed" />

At first I thought it was a date form issue with published_time, but the field appears to follow the time format Facebook uses in their example. I'm not sure what is generating this error. Does the order matter?

UPDATE: I marked the answer below as accepted because clearly people solved this problem with his fix. However, this wasn't the solution that worked for me. This Stack Overflow open graph answer did the trick.

Solution

My solution sounds weird but I solved this using trim, the problem was in the title, my title was something like "My title ". After trimming the string everything worked fine. It seems to me that Facebook parser doesn't like spaces... try it at least, look if that fixes the bug for you.

Hope that helps!