Why Ubuntu 16.04 installer not recognizing unallocated space?

I want to install Ubuntu 16.04 on an un-allocated space which I can see in Windows disk manager as following (78GB)

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I also checked GPart software in live Ubuntu which is showing following picture. cant see 78GB un allocated space. Its showing 113GB space. Dont know why.

Same is the installer. I can not click on + icon to create a partition on un allocated space.

Can some one please advise on it? Is it due to number of partitions in Windows. Should I need to delete more partitions in Windows so that Ubuntu installer may recognize it?