In the dialog for editing the document type properties, in the bottom section there are a series of tabs. The first one refers to the schema that is used for validation of the documents that match the defined Association Rules.
If the document refers a schema, using for instance a DOCTYPE declaration or a xsi:schemaLocation attribute, the schema from the document type association will not be used when validating.
Select from the combo box the value XML Schema.
The ${frameworks} variable is expanded at the validation time into the absolute location of the directory containing the frameworks.