There are four attribute groups is FM2006 as you'll see in the
fm colours.xml file (which is in ...\Football Manager 2006 Beta Demo\data\settings directory):
<!-- profile attribute colours -->
<colour name="
low attribute " red="255" green="84" blue="92"/>
<colour name="
normal attribute" red="255" green="255" blue="255" />
<colour name="
good attribute" red="255" green="255" blue="0" />
<colour name="[B]excellent attribute[B]" red="0" green="255" blue="0" />
Here, low attribute contains the values from 1 to 5, and the others 6-10; 11-15; 16-20 respectively. The skin you've applied is for FM2005 and has only three attribute groups. This must be the reason why some attributes are blank.
I'm not sure but you can try to add the missing attribute group to the fm colours.xml file of the skin to solve the problem. Nevertheless, it's possible that there will be more problems because of the differences between FM2005 and FM2006; so it's best to use the default skin for the demo
imo (till someone revises the old skins for FM2006

).