I am writing my first XSD schema file for validating incoming orders for product and/or literature. My error seems to be related to identifying a sub-grouping of order items - I want one sub-group for Products and one sub-group for Collateral (literature). I thought I was following an example but somewhere I'm not referencing the ComplexType ("t:ProductDetails" and "t:CollateralDetails"). Can anyone see what I'm doing incorrectly? The error I'm receiving first is:
"t:ProductDetails" must refer to an existing simple or complex type.
The XSD file is attached.