Recombulator can't possibly be displaying the correct percentage.

I bought 30 bone rings with 40% minion damage, 30 bone rings with 14+ minion attack speed, (prefix+suffix) and the recombulator said I had at least a 23% chance to combine them, yet all 30 failed.

Then I decided for science to try it 10 more times, and all 10 of those failed.

So either I need to buy a lottery ticket since its a ~0.00002 chance to not get a single combine over 40 attempts, or the percentage displayed is completely wrong.