This may fix your problem:
From what you say: "I double checked the TWO patches", you may be using an older uc_event.
Download the uc_event that New Zeal posted above:
http://www.ubercart.org/files/uc_event_1.zip
This works with the latest Ubercart seemingly with no other issues.
It only needs the ONE patch line in uc_product.module as shown at the bottom of the README and should then work fine.
Hope that helps