Unable to communicate with Sharepoint Server

Hi,

I am unable to test connection the sharepoint site in AX 7.

When i click Test Sharepoint connection button in DocuParamaters, it throws, Unable to communicate to the sharepoint server.

I tried debugging this, and Proxy is not generated . It is null, and fails to connect here.Please refer the below code.

System.UriBuilder builder = new System.UriBuilder(SITE_ADDRESS);
str host = builder.Host;
str extId = xUserInfo::getExternalId();
ISharePointProxy proxy = SharePointHelper::CreateProxy(host, '/', extId); // Proxy returns as Null


Could someone let me know, why the sharepointHelper is not creating the proxy.

Thanks,