You need to have unallocated space on the disk with the partition the size of which you intend to increase
This article applies to:
Acronis Disk Director 11 Home
Introduction
You need to have unallocated space located physically on the disk with the partition the size of which you are going to increase.
If there is no unallocated space on the disk, you will need to shrink a different partition to create unallocated space first. And then increase the desired partition size.
Solution
First, make sure that there is unallocated space on disk with the partition that you want to increase.
When you have unallocated space on disk, you can increase the size of the partition: