dtc issues

[solowma]

Ok, this is my first question and probably not my last.
I recently got the dst and mxscan. Now I have an engine light on my truck that is on and went into the mxscan to look what it is.
The fuel status works. I don't know about the readiness test and why is there a big blank screen in the middle of the window. I am expecting something to pop up there.
Now, I do a check dtc and two problems come up. I would expect more dtc codes to be monitored but I guess I am wrong. The ones that come up are catalyst monitor and egr monitor. They both say true and I have shut of the egr monitor on the dst but can't find the catalyst monitor.
Is there suppose to be something that pops up in the main window? What do I need to change in the dst? Why doesn't mxscan come up with codes for dtc?