Fail to do Volume of Revolution when rotate in y-axis by using student calculus 1 packege.

It is good in any x-axis thorugh.

the erorr looks like this, I follow the direction on Maple website and enter axis = vertical, but it give me something like this.

I type vertical := x = 0 somewhere, I was wondering the Maple think vertical = x = 0, so O change the
vertical := x = 0 to v := x = 0(like first image), but after I run the whole thing it still give me same error.

The weirdest part is I actually run the second one scuccess first time, but second time it failed and I don't know why. I input exactly samething but it failed, weird!!