The message appears when you are welding patterns.
 

• The patterns do not overlap. Rearrange them so the selected patterns overlap. Unifying the pattern, instead, can be an alternative editing method depending on your project.
   
• A pattern that has a seam allowance is selected. Deactivate the seam allowance setting and weld the patterns.
   
• An open shape is selected as a pattern. Only closed shapes can be welded. Unifying the pattern, instead, can be an alternative editing method depending on your project.