pixelformat is invalid when calling wglMakeCurrent

Hi All,

I have a mainform with two clientforms both with a panel on it.
The panel is used to render to.

When a clientform is created I use this code to init opengl/render:

clientform0_Panel_DC := GetDC(clientform0_RenderPanel.Handle);
clientform0_Panel_RC := CreateRenderingContext(clientform0_Panel_DC, [opDoubleBuffered], 32, 24, 8, 64, 4, 0);

ActivateRenderingContext(clientform0_Panel_DC, clientform0_Panel_RC);

CreateRenderingContext sets PixelFormat and calls wglCreateContext.

ActivateRenderingContext calls wglMakeCurrent(clientform0_Panel_DC, clientform0_Panel_RC);

So far everything is fine.
Opengl renders to the panel on the clientform.
Nothing wrong here.

When I create a second clientform I call the same code as shown above but clientform0 is replaced buy clientform1.

Now Opengl renders to the second panel on clientform1.
Still nothing wrong, but when I click on clientform0 I call
wglMakeCurrent(clientform0_Panel_DC, clientform0_Panel_RC);

I expect Opengl renders to the panel on clientform0 again but instead I get an error message like ‘The pixel format is invalid’.

Any idea why I get this error?