MouseDown is not responding properly in this control

Greetings every1,
I'm trying to make a custom CheckBox. So far I've been able to successfully draw the checkbox and the checkmark. The problem is, if u closely observe the CheckBox control included in the Windows environment, u will notice that whenever the user presses the mouse on the checkbox(MouseDown event), the checkbox window changes color to the checkbox color(vbButtonFace by default). In my checkbox, when i press the button, the control changes color sometimes and sometimes it does not. I dont know what the problem is and why its behaving like that. I'd like u guyz to take a look at it. Click the checkbox a couple of times. U'll see that occasionally, the check box window remains white and the checkmark appears. Plz help me. The project is included. Thanx in advance

I'm a little confused by your post. The "checkbox window" changes color as you stated. Then you said that sometimes the control changes color and sometimes it does not. What exactly do you mean by that?

On my computer, the "checkbox window" always changes to vbButtonFace when I click and changes back when I release the mouse button. The little checkbox with the check in it turns a sort of off-white and changes back also.

How do you want it to behave differently? Or is it just your computer that it's malfunctioning on?