I can find all sorts of great DL routings on ITA and Kayak, but when I either try to replicate on Delta.com or clickthrough on Kayak I fail. Either the price has changed, a website error, or magically the fare class has changed to a higher class.

I'm new to Delta....what am I missing here? I'm doing 4 STL-SYD runs to make DM and trying to get the best routings possible.