problem to change the button theme

problem to change the button theme

Hi Friends,
       In my IPad application i have a problem to  change the button theme. On click event i want to change my button theme "a" to "c".
I have include the link to source code of jsfiddle site. Please visit and give me the solution of this probleml. 


Click here to view the   Source.
Click here to run the application  Model Appliction
-Kamalakannan.M