If a message appears "Failed to create the 3D DEM View dialog. Please ensure that the AVIS2D.ocx control is registered on your computer" then for some reason AVIS2D.ocx is not registered on your computer. Reasons for this could be limited privileges when installing IRRICAD or another program interfering during the installation. (It is always a good idea to turn off other programs and even your anti-virus software during the installation process). Another cause could be a subsequent Windows update de-registering the file.
You can register this file manually.
a. Log in as Administrator.
b. Run a Command Prompt by searching for cmd and then right-click on cmd.exe and select Run as Administrator.
A DOS window will open up.
c. Now type in cd C:\ <enter>
cd program files <enter>
(note if your computer is 64 bit type "cd program files (x86)"
cd aei software <enter>
cd Irricad Pro 16<enter>
(note type in the correct Irricad folder path name for where your Pro version is install - it may not be Pro 16 or AEI Software)
regsvr32 AVIS2D.ocx <enter>
It should tell you that AVIS2D.ocx is now registered successfully.