Not able to use Boolean difference

not able to use Boolean difference. as i use it. it does not cut the ribbons(Blue) from the red part. In fact it shows exclamation marks. plz help me to remove those too. let me know what and blue and red exclamation marks. Capture

Hi -

When you select one of these dots, you will see more information in the Properties panel.
For Booleans to succeed, there must be a clear intersection between objects. Run the Intersect command to see where the resulting curves (1) or open and (2) don’t end up on the edge of a surface.
If you need more information, you will have to post the 3dm file…
-wim

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