Stems on young plants - like those most often found in nurseries - are extremely fragile and can be damaged or broken easily, often in shipping/transport or just with normal handling. Without a photo to persuade me otherwise, I'd guess this was the problem.

Purchasing a damaged vine would not be my first choice but it is not an insurmountable problem. The deep planting and the heavy pruning recommended for the first couple of seasons encourages additional or replacement stemming from the root crown.

And as an aside, I find the abbreviating of clems to just the first couple of initials unnecessarily confusing - I have no idea what EM or VV means with respect to the literally hundreds of cultivars on the market without taking extra time to think about it and I am considered pretty knowledgeable regarding these plants - what this may mean to a newbie I can only imagine! Could we please spell out cultivar names if the reference is required?

Thank you for the information and your advise. Actually, I do agree with you on using initials as is not the best way to describe. I'll admit I was in a hurry and tried a shortcut.
The clematis I was trying to describe were Venosa Violacea and Ernest Markham.The Ernest Markham was the one with this problem but I will look at it again. The fellow in charge offered a discount so I might take a chance.
Lois