Displaying visual and non-visual component-icons

While developing components, I have noticed that sometimes the icon
(in the DCR-file) is displayed on my form when I select the component,
and at other times it is not displayed at all, but a blank spot is
displayed. I can get the icon back if I put it in a resource-file
(RES), but it is not being displayed in the usual button-look of
Delphi as we can see with the other components. I have noticed that
this behaviour occurs when the component I created is visual, but I
don't know if this is the only case where it happens. Does anyone have
a work-around for this kind of behaviour, because I would like to see
my components at all times, visual or not.

Thanks,

Harrydath B. Ghisaidoob