Doesn't sound right, indeed! A Record being created in the Main Form of a Main Form/Subform configuration does require that a Record being entered in the Subform. You may see the Control holding Foreign Key Field populated by that data, as determined by the Main Form Record...but a Record in the Subform is not actually created unless some other Field is populated...no 'blank Record' is created.
As orange said...more details and, preferably, a copy of your database, are needed for us to help you.
Linq ;0)>
The problem with making anything foolproof...is that fools are so darn ingenious!
All posts/responses based on Access 2003/2007