Hi Rob,
Thank you for your interest in Syncfusion products.
Please refer to the following link that demonstrates why this issue occurs and the steps to resolve this.
http://msdn.microsoft.com/en-us/library/cc917670.aspxIn this page please check "HTTP Connectivity->Error Condition 2: IIS Anonymous Connection Not Permitted" to resolve this issue.
Please let us know if this helps.
Thanks,
HariVenkatesh