Interesting. You should know this though. I just put in an order for TRKG with Scottrade 5 minutes ago and it took my order just fine. It should be noted I bought TRKG months ago via Scottrade. Maybe it lets me buy more because I already own TRKG via Scottrade.
I've owned TRKG through Scottrade for months and just made both buy and sell transactions with it within the past two weeks. Not sure when this took effect.