Cannot boolean union my solid. Pls help.

 From:  Rudy
2361.1 
Hello all,
Rudy here.
I include the 3dm file.
Basically, when I try to boolean union my flower (petals and all), only three petals and the center get unioned. The one at 6 does NOT.
Why it that?
Can somebody help me to fix the problem?
Thank you in advance,
Rudy