Umbraco CMS and Salesforce Web-To-Case functionality- issue sending data to SF

We are using Umbraco CMS and Contour (Form Creation) and the idea is that a submitted form goes into Salesforce using the Web-To-Case functionality.

Added SF endpoint URL to Contour and the Salesforce OrgID and other obligatory SF fields as a hidden fields in Contour.

However, no cases are being created in Salesforce, has anyone else had experience with using the Umbraco CMS system in conjunction with Salesforce? Or can help out here with a settings checklist?

Thanks,

Dave