First off check if you're getting a reading at the boot, If not trying earthing the multimeter straight to the chassis. If still no reading it will be a +ve problem and not an earth issue.

Double check the fuse, I've had fuses look fine before now but have a tiny break. Try a new fuse.
If that doesn't help then you need check continuity along the live with you multimeter to see if there's a break along the wire somewhere.

ok will do thanks mate,but if it still dosent work then what do i cheack then??

Have to you checked the 2 connectors on the rear window? One's the live from the switch, The other is an earth which bolts to the bootlid.
Get a multimeter on the connections to see if you get a feed with the demistor switched on.

mine dosent work at all tho

Mine's the same mate, only the bottom two lines work.

my rear di-mister dosent work, iv cheacked the fuse and its all good and not broke,and the light on the switch comes on when i pull the heater nob out,im sure when i got the car the rear heated window worked,but now iv fitted epas it dosent lol.

Its really annoying at this time of year not haveing it working.thanks for your help muchly appricated.:thumbs: