Error enabling Smart Queue

I'm unable to enable Smart Queue on my ERL running 1.9.0.

I've tried via the WebUI, and receive a very vague error, "Failed to apply the configuration".

When I try via the CLI, I get this:

admin@EZMSRouter# commit
[ traffic-control smart-queue sq1 wan-interface eth2 ]
eth2 should be only used in one QoS policy!

I don't have any other traffic-control or traffic-policy settings whatsoever, so I'm not sure why I'm getting this.

Here's the relevant portion of my show command:

+traffic-control {
+    smart-queue sq1 {
+        download {
+            rate 15mbit
+        }
+        upload {
+            rate 2mbit
+        }
+        wan-interface eth2
+    }
+}
[edit]
admin@EZMSRouter#

As you can see, I'm adding the traffic-control policy in general, so I'm not sure why it thinks that I already have a policy applied to it.

Any help is greatly appreciated!!