求助：划分网格失败

UG中用曲线组建的模型，转成x_t后导入workbench，在网格划分的时候总是失败，提示：The following entities failed to mesh. The meshes of the bodies containing these entities are not up-to-date. However, meshing may be successful on the other entities.和The mesher did not generate any nodes. All geometry may have been defeatured away.求教！