textures directory contains SH3T files so it's not a problem.

what could be wrong?

You have to copy the preferences.xml file too.
If the destination computer runs Windows 7, the destination directory should be
C:\Users\user\AppData\Roaming\eTeks\Sweet Home 3D where user is your user name.

Caution! Once preferences.xml is copied on the destination computer you'll will loose all the furniture and textures you imported on that computer. So create a backup of Sweet Home 3D directory first.