For flash themes to work you need the SWF and thm file
then use:
XS++ 3.1 Guide-Flashing,Customizing,Recovering - Top Sony Forums
to flash the file on.
Look at number 5
;Flash Menus -> 'TPA/PRESET/SYSTEM/DESKTOP/FLASH'.
Only the SWF file goes there ^
The THM goes in the theme folder in the phone or memory sticka and then you set the theme.