Java nullpointerexception on loading imported blender model

Hi, I’m new to jMonkey and I need help to solve this problem :
I exported a blender model to ogre mesh file using the plugin provided. The export worked, I got the mesh.xml and .material file on the output folder.
Then, I dragged the files into jmonkey’s project assets folder and tried to load the object into the game using this code :

 Spatial firewood;   
firewood=assetManager.loadModel("Models/firewood/Cylinder.007.mesh.xml");
    rootNode.attachChild(firewood); 

At first, the material file was named “wood.material”, and jMonkey popped an error telling me that the mesh has no .material file, so I changed the material file to the mesh file name “Cylinder.007.material” ( the mesh name is “Cylinder.007.mesh.xml” )
But then I encountered this error and the game window closes immediately

Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: alpha_to_coverage
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: colour_write
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: depth_check
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: depth_func
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: depth_write
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: illumination_stage
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: light_clip_planes
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: light_scissor
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: normalise_normals
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: polygon_mode
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: scene_blend_op
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: shading
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readPassStatement
WARNING: Unsupported pass directive: transparent_sorting
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readTextureUnitStatement
WARNING: Unsupported texture_unit directive: scale
Oct 25, 2014 12:37:43 AM com.jme3.scene.plugins.ogre.MaterialLoader readTextureUnitStatement
WARNING: Unsupported texture_unit directive: colour_op
Oct 25, 2014 12:37:43 AM com.jme3.app.Application handleError
SEVERE: Uncaught exception thrown in Thread[LWJGL Renderer Thread,5,main]
java.lang.NullPointerException
	at com.jme3.scene.plugins.ogre.MeshLoader.applyMaterial(MeshLoader.java:215)
	at com.jme3.scene.plugins.ogre.MeshLoader.startSubMesh(MeshLoader.java:284)
	at com.jme3.scene.plugins.ogre.MeshLoader.startElement(MeshLoader.java:652)
	at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.startElement(AbstractSAXParser.java:506)
	at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(XMLNSDocumentScannerImpl.java:376)
	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:872)
	at com.jme3.asset.DesktopAssetManager.loadAsset(DesktopAssetManager.java:282)
	at com.jme3.asset.DesktopAssetManager.loadModel(DesktopAssetManager.java:410)
	at com.jme3.asset.DesktopAssetManager.loadModel(DesktopAssetManager.java:420)
	at mygame.mainMenu.fire(mainMenu.java:164)
	at mygame.mainMenu.initialize(mainMenu.java:123)
	at mygame.Main.simpleInitApp(Main.java:44)
	at com.jme3.app.SimpleApplication.initialize(SimpleApplication.java:228)
	at com.jme3.system.lwjgl.LwjglAbstractDisplay.initInThread(LwjglAbstractDisplay.java:129)
	at com.jme3.system.lwjgl.LwjglAbstractDisplay.run(LwjglAbstractDisplay.java:205)
	at java.lang.Thread.run(Thread.java:722)

Oct 25, 2014 12:37:43 AM com.jme3.renderer.lwjgl.LwjglRenderer cleanup
INFO: Deleting objects and invalidating state
Oct 25, 2014 12:37:43 AM com.jme3.input.lwjgl.LwjglMouseInput destroy
INFO: Mouse destroyed.
Oct 25, 2014 12:37:43 AM com.jme3.input.lwjgl.LwjglKeyInput destroy
INFO: Keyboard destroyed.
Oct 25, 2014 12:37:43 AM com.jme3.system.lwjgl.LwjglAbstractDisplay deinitInThread
INFO: Display destroyed.
AL lib: ReleaseALC: 1 device not closed
BUILD SUCCESSFUL (total time: 2 seconds)

I’m using blender 2.69 and the v0.6 plugin.
any clues / solution would be great, thank you.