InfoPath Dev

I'm trying to create an InfoPath form for publication on a SharePoint site.

I create the form and run a design checker. Get no errors.

Select Change Settings, highlight Compatibility (auto) and select Web Browser (auto). I enter the main part of the URL. I get an error "Could not verify the form template on the specified server."

Change Settings again, I try Web Browser (InfoPath 2007). Same error.

This is one of many errors I'm having. Been trying to publish an InfoPath form to SharePoint for about a year now without luck. Really need step by step instructions (that work).

Thanks.

I've gotten the error about not being able to verify the form template on the server before, but it hasn't blocked me from publishing. What happens when you try to publish? Are errors then returned to the design checker?

I can publish it, but when I go to Submit it, I get another error.

"Infopath cannot submit the form"  Details: InfoPath cannot submit the form.
The form was not submitted because a form named Form.xml already exists in the document library at [URL]. Please contact the provider of the form.