If you live in the United States, then it is probably OBD-II. If you live in Europe, probably not.
All cars sold in the United States since 1996, and sold in the European Union since 2002 are mandated to comply with OBD-II.
Here is some information that might help you to figure out whether your car is compatible: https://www.scantool.net/support/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=2&nav=0
If you have a OBD-II car, it is possible that the CLK unit is defective. I would suggest trying it on a newer car if you are able to.
What error message does DashCommand give you when you try to connect?