SOLVED!!
Thank you for your assistance. I noticed that i had not uploaded all the Modules specified in the ReadMe.
Install following required extensions:
- DT Register System Plugin
- DT Register EventLink Plugin
- System - DT Register SSL
- DT Register JEvents Update Plugin
- System - DT Register No Cache Plugin
- DT Cart Module
- DT Register Upcoming Events Module
- DT Register Search Module
- DT Register Calendar Module
When I added that to the system the error went away.
Atilla