lucy24 - 8:10 pm on Sep 19, 2012 (gmt 0)
My robots.txt file is a simple 2 line
file that contains a "*" for User-Agent, and the 2nd line lists the URL of my sitemap.
I hope you mean a 3-line file, where the second line is
followed by nothing. In any case, since you seem to be letting everyone in, why not see what happens if you take the other tack and delete the robots.txt file? Google doesn't mind if you don't have one at all. They only get upset if they can see it's there but have a problem reaching it. Sitemaps are similarly unessential-- and if they're in the default top-level location, search engines will find them even without haha a map.
The other possibility is that although it's got the name "robots.txt" you have inadvertently saved it in some other format, so google can retrieve it but can't read it. What do you see on the tab of gwt that is supposed to show the content of your current robots.txt?