# Error in integral

I've got this error on the second integral. I put the code on wxMaxima and returned sucessfull. On wxMaxima, raise a question "z is positive, negative or zero?", also on sage, but on sage I can't answer that. How can I correct this?

`x,y,z = var("x y z")`

`function = x*e^(-y)`

`integral(function,y,0,ln(x)).integral(x,0,2*z)`