I hate the word No!

My conversation with Reagan during bath tonight:
Me:Reagan are you playing in the tub!?
R: No
Me: Yes. Yes you are playing in the tub!
R: Yes
Me: Reagan are you playing in the tub?
R: Noo
Me: Yes, yes, yes you are!!
R: yes
Me: Are you playing in the tub?
R: No
This is how it goes most of the time. I can not get this girl to say the word yes on her own! I am so frusturated. Some day hopefully I will be able to say that she has said something other than no to a question! On a better note....she figured out how to climb up on the couch tonight! So within a few hours her new favorite activity is climbing on and off the furniture.