You have to import BTN and DISBTN.
Change paths for BTN to: ReplaceableTextures\CommandButtons\BTNStormReach.blp
And for DISBTN to: ReplaceableTextures\CommandButtonsDisabled\DISBTNStormReach.blp
If that doesn't work, the path is wrong, or there is a problem with your icon.
Remember, you must have 2 Icons, BTN and DISBTN.