Sheet Metal Design模块求助

CATIA V5R20 Sheet Metal Design模块，草图基础上无法生成基体件。求教！！！
提示：you are trying to create a sheetmetal paer in the sheetmetal
          design workbench
           sheetmetal parts can only be created in the generative
          sheetmetal design workbench
          please select generative sheetmetal design woekbench to
         create your new park

到GSD模块画草图