add web reference for HTTPS

Hi,

I created a Java webservice and I success to connect and use it via Web Reference with HTTP access. So now I switch to HTTPS access by creating a self-sign certificat (via keytool) I can successfully connect and use the webservice via SoapUI

But when I try to connect via Xamarin I receive the following message:

this is normal because I self-sign the certificate so I click on "Yes" but after I received the following error:

Can somebody help me ? is it possible to include the certificate somewhere in Xamarin config ?

Thanks for your help