Problems graphing a surface of revolution

[Nikki]

When I try to create the mesh I get this warning:

"This value has the form: (volume, volume, volume, unitless, unitless), but must have the form: UniTup5 volume. "

I don't understand what this means. The function is graphed, but I don't know how to revolve it.

*file attached with mathcad document

[ViktorKorobov]

You must define the variable L.

[Nikki]

Thank you so much! I've been trying to figure that out for a few days now.