different random background on each monitor

When i bought this, i was under the impression, that because it supported multiple monitors, and supported random backgrounds...that it would support different random backgrounds on multiple monitors.

However no matter what i have tried, i can't seem to get it working how i hoped.

- I can have a non-changing background on some monitors, and a random changing background on one monitor.
- I can have the same random changing background on all monitors.

If there is a way to get what im looking for please let me know...if not i feel quite let down after buying this.