Comment 3 for bug 138910

As far as I know the PSI-desklets (as well as the LT-desklets) do not work with newer version of gDesklets (and with newer I mean 0.33.x or 0.34.x and up).
These desklets are based on Sensors (either PSI sensors or LT sensors) and Sensors are depreciated since gDesklets 0.30 and will be no more supported with gDeskelts 0.40.
So the problem here is that this desklet (and other desklets) has never been updated to use Controls and to be working with gDesklets 0.3x.
If you are looking for further (and subtotal !) information if a desklet is working with the current release of gDesklets take a look at the "unofficial gDesklets Desklet Archive" (the link can be found on the gDesklets homepage under "Archive for older desklets").