BooleanUnion Failed After Baking and "no valid volume"

Hello guys,

After doing this script,I need to 3d-print it for submission. However, after I bake it, it always said"Boolean failed" and when I put it into Netfabb, it shows "no valid volume" as below, Can anyone help me to fix it up? It's due in two days. BIG THANKS!!!

P.S. The original script is attached.

Sincerely,

Colin