1:M relationship being automatically converted to 0:M! Why?

[Nefarus]

Hi,

This is a newbie question. here is the problem. I have reverse
engineered two tables on a visio data modelling sheet and am trying to
place a relationship that states the relationsip as 1:M.

The problem is that when I link up the relationship to the tables, the
relationship automatically converts itself to a 0:M? Why? How can I get
around this? Is Visio checking the data in the database and trying to
say that the existing data supports a 0:M relationship?

Any help would be greatly appreciated.

Thanks!