You need for someone to pickup the paypal provider and do some research on it: https://nbstorepaypal.codeplex.com/SourceControl/latest
My thought is it's related to the advanced url rewriter, which is known to be a little odd at times, I would try and see if you can change the config of that to not re-write urls with "stg" param. (Never used it so I'm not sure you can, but there is some regexpr settings in the web.config)
As for other payment providers, it depend where you are?...if in Europe I would opt for a SIPS based solution, they tend to be bullet proof. If in the US then you'll need to check which provider will suit you best, have a look at related projects on the home page. https://nbstore.codeplex.com/ But be aware that although I've heard Authorize.Net does work well, it's an awkward one to setup.
My thought is it's related to the advanced url rewriter, which is known to be a little odd at times, I would try and see if you can change the config of that to not re-write urls with "stg" param. (Never used it so I'm not sure you can, but there is some regexpr settings in the web.config)
As for other payment providers, it depend where you are?...if in Europe I would opt for a SIPS based solution, they tend to be bullet proof. If in the US then you'll need to check which provider will suit you best, have a look at related projects on the home page. https://nbstore.codeplex.com/ But be aware that although I've heard Authorize.Net does work well, it's an awkward one to setup.
