Updated ConvertMaterials function to assign appopriate material index when using material references.

code/AssetLib/X/XFileImporter.cpp

@@ -580,7 +580,7 @@ void XFileImporter::ConvertMaterials( aiScene* pScene, std::vector<XFile::Materi
                 aiString name;
                 pScene->mMaterials[b]->Get( AI_MATKEY_NAME, name);
                 if( strcmp( name.C_Str(), oldMat.mName.data()) == 0 ) {
-                    oldMat.sceneIndex = a;
+                    oldMat.sceneIndex = b;
                     break;
                 }
             }