I have been using UD 994 with Z Wave for awhile w/o any issues but decided to switch to the Hubitat. i can't seem to any a Z-Wave device to this Hubitat. I have new never used zwave devices and it says adding then stops. i have gone down the path of adding by manufacturer, Device Type and scanned in code on phone. they NEVER add
I'd suggest an exclusion first, as mentioned above (even if it's new). You might also need to check that the device matches your region, as Z-Wave has a few different frequencies around the world. See also: How to Troubleshoot Z-Wave - Hubitat Documentation (ghost nodes would be good to check for, too)
The manual for the device will usually tell you how to run an exclude. Often it's the same steps on the device as pairing, but with a Z-Wave hub in "exclusion" mode (it can be any working hub, not just the previously paired one).
I have noticed with the C-7 model Habitat hub that it's a good idea to reboot it after one or two failed inclusions. Make sure to check the linked page posted by Bert above on ghost devices, as it's a pretty common situation when you've had several failed pairings and it can significantly impact inclusion.
Be sure to check for failed pairings in Settings > Z-Wave Details. For you, these will likely be rows (nodes) without a linked device in the Device column. There should be a Remove button; if not, a Refresh or two should make one appear, or if you wait a while it will likely change on its own when it fails to hear back from the device for a while. Just mentioning this since "ghosts" have been known to (though not necessarily) cause problems and it sounds like you've had a few unsuccessful pairings that may have created some (or at least something bad if you are strict on terminology :D).
My advice is to go from device to device - Factory reset then add that device to Hubitat. Make sure that you keep your Hubitat close to the device you are including. You can heal the network later when you install all your devices. I use a long ethernet cable and a portable power source. It works great.
@SteveP Are your devices z-wave or z-wave plus? If z-wave they can not be excluded/included via repeaters they need to be paired close to the hub. Also did you exclude or reset your devices first? (Make sure you turn off your old hub first) Please take a gander at this
I am huge Insteon guy who moved over. Hubitat does not support Insteon but I will tell you on eBay you get near full retail for those devices. So I would sell them on eBay and buy Zigbee switches. I also like the Lutron Caseta solution with a Hub Pro but it is much more expensive.
If you want to work with Insteon/ISY and Z-wave there are two solutions. Homeseer with the ISY plugin or Home assistant with a Z-wave/Zigbee stick (using the ISY). Both are much more complicated. I would recommend removing and selling your Insteon and buying Zigbee replacements. I do like Zigbee over Z-wave; it works better with less headaches. When you switch to Hubitat you will never go back.