|By the way you should not double post, it causes confusion.|
There is a difference between free space and unallocated space.
To extend your partition you need to have unallocated space.
The reason you have free space is that you probably have an extended partition in which you originally had a logical drive.
You have deleted the logical drive creating free space in the extended partition.
To turn that free space into unallocated space you need to delete the extended partition first.
You should be able to do this in disk management.
☺ When everything else fails, read the instructions.