Hi Amaes,
When you create a custom scale, it becomes part of the DAQmx Task created when using the DAQmx Create Virtual Channel. Thus, once the task has been started, the scale is committed to the task just like the timing or sample mode. In order to change the custom scale used by the task, you must stop and clear the task. You can then reconfigure everything you need (acquistion rate, sample mode, scaling, etc.) and create a new task with this information. Simply stopping the task does not clear the settings, so even though you are writing new values to the scale, they will not take effect until the current task has been cleared.
Donovan