Occasionally, a solid model can be imported that looks good, but is not a valid solid. That can cause problems performing further solid modeling operations or recognizing features from the solid. To check that the solid is valid:
Select Verify solid from the Solid submenu of the Construct menu or click the Automatic Feature Recognition
button.
Click the Verify button.
A dialog box is displayed indicating if the solid is valid.
Click Cancel to remove the dialog box.