I still have no idea which Windows OS you're using. Remember with Vista you need to be logged in as Admin. And in some cases need to set the installer to Admin by right clicking it. Sometimes also need to change compatibility mode of the installer. Sounds silly but sometimes that works.

Vista 'requires' Java 6.

If using XP or earlier, perhaps you could try the earlier version Java, namely JRE 5.11 offline version Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11 (Choose JRE version)

Something else to try, though it probably will not make any difference if LW is not seeing Java, Download ‘Other’ version & simply unzip & use!