Extension Methods & Pointers

[code?]

Okay, so I'm having this problem.

I defined this animation function (similar to jQuery if you have heard of it) for controls. Notice: I condensed the code into one box, the two methods are in two different classes.

private unsafe void FormMain_Click(object sender, EventArgs e)
{
    this.Animate(&Width, this.Width + 50);
}

public static Control(this Control C, int* Property, int Value, float Time)
{
    // Calculate Steps
    &Property += 50;
}

Now, the way I have it set up is that you can pass a property by reference, so that the function can edit it directly, instead of use a copy, right?

It keeps giving me an error in the FormMain_Click:

"Cannot take the address of the given expression."

Please help. Also, if I was to get this working correctly, I don't know how to get the interval set correctly. It has to do with dividing the Time by the property and the value passed, but I don't know the algorithm.