Dual Boot Error

I have Windows10 Toshiba Laptop,I want to dual boot windows 1o with KALI LINUX.I had so many issues before reaching this point,It took 2 months to Resolve all those problems.Finally I reached this point,But now this error.

I reached the point where you divide the partition,I used Disk Management to partition the free disk space,While in installer the free space shows unusable And I am unable to do anything.Please help,or all my 2 month work will be spoiled.Please Help!