Use exactly the same "SchemaLocation" attribute value used in your WSDL in the "SchemaLocation" attribute of the "resource" element of the "publishWSDL" option.
For example, if the WSDL has a the schema imported as,
<schema namespace="some_namespace" schemaLocation="./TestSchema.xsd">
Then the "schemaLocation" attribute of the "resource" tag should also have the same as mentioned below.
<resource schemaLocation="./TestSchema.xsd" ...>