How to import and convert mesh xml file into models

hi friends,
firtly i apologize for my english.
I ’ m trying that import mydesign.mesh , mydesign.material and mydesign.xml files to jmonkey engine sdk 3.0 rc2 in project assets/models and i’m right clicking and convert to j3o binary but I get an error…

I’m using sketch up 8 and ogre exporter for sketch up plugin and windows 8 .

“An exception has occured while loading assets”
Details ,

"
org.xml.sax.SAXParseException; lineNumber: 272104; columnNumber: 28; The value of attribute “material” associated with an element type “null” must not contain the ‘<’ character.
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:198)
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(ErrorHandlerWrapper.java:177)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:441)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:368)
at com.sun.org.apache.xerces.internal.impl.XMLScanner.reportFatalError(XMLScanner.java:1388)
at com.sun.org.apache.xerces.internal.impl.XMLScanner.scanAttributeValue(XMLScanner.java:906)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanAttribute(XMLNSDocumentScannerImpl.java:436)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(XMLNSDocumentScannerImpl.java:253)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2717)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:607)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:116)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:489)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:835)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:764)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:123)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1210)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:568)
at com.jme3.scene.plugins.ogre.MeshLoader.load(MeshLoader.java:888)
Caused: java.io.IOException: Error while parsing Ogre3D mesh.xml
at com.jme3.scene.plugins.ogre.MeshLoader.load(MeshLoader.java:897)
at com.jme3.asset.DesktopAssetManager.loadAsset(DesktopAssetManager.java:283)
Caused: com.jme3.asset.AssetLoadException: An exception has occured while loading asset: Models/test.mesh.xml
at com.jme3.asset.DesktopAssetManager.loadAsset(DesktopAssetManager.java:285)
at com.jme3.asset.DesktopAssetManager.loadModel(DesktopAssetManager.java:369)
[catch] at com.jme3.gde.ogrexml.OgreXMLDataObject.loadAsset(OgreXMLDataObject.java:102)
at com.jme3.gde.core.assets.actions.ConvertModel$1.run(ConvertModel.java:63)
at java.lang.Thread.run(Thread.java:722)
"

please help me , I'm working since the morning.