New Post: Go to Checkout fails

I really don't know what's wrong here and I haven't seen this problem before.

I've checked all of this on my DNN 7.1 test instance and everything works, including changing the rewriter to advanced mode, which allows extension removal and finally inserts dashes for spaces.

However, I think it is definitely to do with URLs.

You should be able to browse any DNN instance by way of tab IDs.

For example, this is the checkout on the demo site:
http://ecommerce.nevoweb.com/tabid/86/Default.aspx

And this is the homepage:
http://ecommerce.nevoweb.com/tabid/56/Default.aspx

Your checkout page is this - but it doesn't work:
http://www.dstroketennis.com/tabid/100/Default.aspx

And your store page is this - also no go:
http://ecommerce.nevoweb.com/tabid/86/Default.aspx

If you can figure out why your site doesn't allow those URLs then that will be the answer for this problem.
My own DNN 7.1 instance works with these URLS.

I would be looking into your hosting arrangements. Is it shared.. did you configure IIS etc.
Rob