[pmwiki-users] Unable to load new skins

[pmwiki]

I am getting the following error with every new skin that I have tried 
to load:

PmWiki can't process your request
Unable to load [NameOfSkin] template
We are sorry for any inconvenience.

Skins that I loaded earlier work fine. 

All skins are located in the same place and I am using Hagan's 
alternative that builds a list of skins automatically in config.php  The 
problem is not resolved by substituting a manual $PageSkinList array 
together with skinchange.php.  (I can't get Pm's new alternative working 
yet).

All skins are reset using Pm's new skinlist directive (the revised 
version).  The problem persists if I use hardcoded links or enter the 
?setskin into the address by hand.

I am using 2.1 beta26.  These are the newly installed skins that are not 
working:
NeutralSkin
flckr
lens
light
monobook

And these are the previously installed skins that still work:
beeblebrox
fixflow
gemini
grease
jhmp
notsosimple
pmwiki
recurve
sinorca

Any ideas what could be going on here?

Pico