Ccleaner not showing all drives

I use external storage on my computer. These drives are mapped as Drive X and Z (see attached screenshot Ccleaner1.jpg)

But Ccleaner only shows C,D,G,H,I & j (see attached screenshot Ccleaner2.jpg)

Any suggestions as to what should I do ?

post-68509-0-42397800-1389429558_thumb.jpg

post-68509-0-00652800-1389429577_thumb.jpg

it doesn't support network drives.