Question: Line Integral

I want to evaluate a line integral of the vector field F:

F: <x^2 * y, x^3, x*y>

around the curve C: <sin(t), cos(t), 1/4(sin^2(t) - cos^2(t))

 

When using Line Integral I got the following error:

 

Error, (in VectorCalculus:-LineInt) the first argument of a Path structure must be a free Vector or a position Vector
 

 

Code:

 

> restart;
> with(plots); with(plottools); with(VectorCalculus);
> SetCoordinates(cartesian[x,y,z]);

>LineInt(VectorField(<x^2*y, x^3, x*y>), Path(<sin(t), cos(t), 1/4* (sin^2(t) - cos^2(t))>,t=0..2*Pi))

 

Not: all "*" is "."  When I type shift-8 on the keyboard (or *), Maple editor give a dot. 

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