How to dock to the top and the left

With An anchor I can write the following line:

myControl.Anchor = (AnchorStyles.Top | AnchorStyles.Left);

And it will anchor myControl to the left and the top.

Why can't I do the following:

myControl.Dock = (DockStyle.Top | DockStyle.Left);

I can write the above line, but all it does is set the DockStyle to left.

Any thoughts/reasons for this?