I'm trying to increase a logical volume that is used for replication, but I'm having troubles.

Both our units have six LV's that are being replicated.
I want to increase the size of 1 LV, so I've stopped the replication process on the source unit for the LV I'm trying to change.

But when I try to modify the LV by choosing the action "modify lv0002", I cannot use the slider to increase the size, nor can I enter an amount of GB to add to the volume.

Is there anything else I need to do?