I followed your suggestion and it does not work. It is still the same issue.
When looking at the xml file, it does seem “right” to me:
...
<view background-offset="0, 0" bitmap="Control_AudioSwitch_50x100" class="COnOffButton" control-tag="Root::Param_AudioSwitch" default-value="0" max-value="1" min-value="0" mouse-enabled="true" opacity="1" origin="130, 120" size="50, 50" transparent="false" wants-focus="true" wheel-inc-value="0.1"/>
...
<bitmap name="Control_AudioSwitch_50x100" path="Control_AudioSwitch_50x100.png"/>
...
Yan