New 6400 not modulating despite DAX input from DM780

AA1UI

Hi folks,
I'm not new to Flex... been going with gusto from 3000, to 6300, and now recently a 6400.  I successfully configured HRD's DM780 for the RTTY contest and made a few contacts last night. However, at one point, I noticed that despite what appears to be signal getting from DM780 through DAX into the transmitter of the 6400, there is no RF being generated. Not a peep.  I'm not sure what happened.  It was working, and then it stopped.  I poked at things for a long while. I even did a full DAX uninstall/reinstall following Tim's method. It worked for a while longer, and then, again, I can't get any RF out despite a heavy level shown coming into the 6400.  I tried increasing the TX stream gain, which at least made the output start to flicker a bit, but by then it was overloaded and distorted, so not the answer.  I just can't figure it out.  It's like it's severely attenuated, but I can't figure out how or why.  I've grabbed a picture of the screen to show you what I am seeing.  DM780 is sending RTTY (with no text... just spinning) and as you can see the TX section sees a nice healthy signal.  There's even a bit of waveform showing on the panadapter.. but not much.  Note there is no RF out despite the rig being in TX mode.  Also, if I hit TUNE and raise the slider, I'll get the full 100watts out with no problem.  Curious eh? de AA1UI

WX7Y

Dave - W6OVP

AA1UI

I'm going to keep fussing with it and see if I can figure out what is going on.  I may have some type of corrupt profile so I'm trying different things there.  Last night, I successfully made my first FT8 contacts using WSJT-X, so at least I know the 6400 can pass DAX info with that program. It's most frustrating when things work, and then they don't all of a sudden.  Thanks all for the suggestions so far.

Dudley WA5QPZ

AA1UI

I have to admit, the whole "sound properties names change" thing is a bit of a mystery.  If there's a definitive guide on that somewhere, I'd love the link.  Thanks Dudley.

AA1UI

So, I appear to have solved my issue. It had something to do with a Mic Profile that I had setup for RTTY that somehow was corrupted as it just wouldn't work.  I switched to my PSK profile, modified it and and I was back in business.  Still scratching my head, but the important thing is I am running on all my fav digi modes once again. Ta freakin' da!  Thanks again for being their my fellow Flex folk.