Cannot get reality for DS to work

To start this here are some specs for computer and Daz studio
Model Name: iMac OSX 10.11.6 El Capitan
Model Identifier: iMac12,2
Processor Name: Intel Core i5
Processor Speed: 2.7 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 16 GB
Boot ROM Version: IM121.0047.B29
SMC Version (system): 1.72f2
Daz studio version 4 9 3 166 Pro 64 bit
Reality the latest version downloaded and installed this morning
The problem is
Couple of days ago I tried to call Reality from DS and was prompted to fill in the registration form. Up till then it had been working fine. I had no idea why this reg form prompt appeared but I filled it in, got a confirmation from Preta that it had been registered and tried to use reality. I got the registration prompt again. And every time I call up reality I get the prompt.
Sine then I have contacted Preta who seem unable to work out what is happening, I have deleted Reality and installed an new version and the same thing happens. I have deleted Daz and installed it again and the same thing happens.
Reality show up as normal everywhere you would expect it to, in the render window above the viewport, in the installed plug ins, even in the content under Reality. All the various extras like lights and such are there. There seems to me to be a problem with the connection between Daz and Reality, I am not technical enough to understand if this is the case or indeed how it works.
What I cannot do is render with Reality. I have no idea if this is a Daz issue, a reality issue or maybe an OSX iMac issue.
Desperately seeking help, anyone have any ideas please
Comments
When you registered with Pret-a-3D, did they not email you a registration number? Registering the software alone will not activate it in DAZ Studio AFAIK. Did you enter the registration number you received in the registration field for Reality under About Installed Plugins? Is the registration number showing in About Installed Plugins after you start DAZ Studio?
Maybe try creating another user account on your mac and installing daz/reality, see if issue persists.
I can't even install the latest Reality on my Mac, and as of a few weeks ago, the one I do have keeps asking me to re-register. Nevertheless, it still works; just another 'Cancel' thing to click every time I start up.
Theres a fix for mac install issues over at the reality forums, may help.
http://preta3d.com/forums/viewtopic.php?f=25&t=644