While working on tutorial 20 , I got an error regarding expressions. expression file .ccl is provided with the tutorial. anybody knows the correction. i get this message as soon i specify dBallNew and dBallOld in default domain and in monitoring points respectively. thanks in advace.

I managed to sort it out. Actually i didn't realize that i must choose the same names while specifying boundary conditions as the name Ball was being used by one of the expressions.