Thank you for your reply Wayne but I don't get it.
You are writing: " I recommend to use an iframe rather than the plugin"
But it seems that Iframe is itself a plug-in : http://wordpress.org/plugins/iframe/
And if I look at the purpose of that plug-in I find this : An IFrame (Inline Frame) is an HTML document embedded inside another HTML document on a website. The IFrame HTML element is often used to insert content from another source, such as an advertisement, into a Web page.
So if I understand, if want to use iframe to display my panorama, it has to be already online somewhere on the web (which is not the case).
Thank you DJIO as well for your reply.
If I understand, you do not have any trouble to display a V2 panorama with Panopress. That's interesting. I had a look at my project, but I didn't set up any domain limitation or protection of any kind.
I am kind of lost for the moment.