just brew it! wrote:
Are you running from the partition you are trying to resize?
I understand that repartitioning Boot Camp must be done from OS X side not from W10, thus the machine is booted to OS X(El Capitan) that is on OS X partition. So, answer is No.
Edit: My further research on iPartition indicates that it cannot make any change on the disk if the iPartition resides on the same physical disk. Changinng disk(splitting partition, creating new partitions, etc) appears possible from a physically separate disk. The separate disk can be that with a cloned OS X where iPartition is installed or a bootable iPartition USB flash memory drive.