This has me beaten. You may have to wait for a WA tech to take a look.
Can you confirm that you have the basic mySql and PHP version requirements (PHP 5+, MySQL 5)?
I'll have a think about this, but I feel that I may have exhausted my ideas at the moment. There may be someone with more suggestions who can offer their insight before the WA guys return on Monday.
I'll post back if anything occurs to me.