I have tried to read GML file using OGC GML reader but I got some errors. I Tried different version reader still the issues coming all those files.

I have tried to read GML file using OGC GML reader but I got some errors. I Tried different version reader still the issues coming all those files.
Hi
A possible reason for the error is, the gml document refers an XML schema file (*.xsd) by URL, but the file cannot be accessed with some reason.
Firstly see if "xsi:schemaLocation" attribute exists in the root element of the gml document and a specified XML schema file in the attribute is accessible over the Internet.