I would like to know this, too. I don't get the error message noted by the OP, I just get the page fully formatted, with images, colors, layout etc. where I would have previously gotten a mobilized version of the page.
When I use the Mobilizer on a regular PC, i.e., in FF or IE, it appears to mobilize the page. It's just on my phone that it doesn't work. My phone is a dash and I"m using Windows Mobile for Smartphone.