Shadow tables

[Beauford]

Hi Everybody,
Although I don't actually need it, (I may use the theory to create routing for my wedding cars) I am trying to create this attached DB from the works of Soren Lauesen.
I create the tables, then the forms as instructed, When I try to fill in the form 'Leg' I keep getting the message "you cannot add or change a record because a related record is required in the table "leg".
What am I doing wrong?
I have a very basic knowledge of Access, but trying to learn from this site and it's really helpful contributors.
Thanks in advance.

 

[spikepl]

Leg 1: From A to B, route # 1, next =2
Leg 2: From B to C, route #2, Next =Null

If you fill out data beginning with Leg 1, then leg 2 is not yet defined, so you need to leave Next (for Leg 1) blank, or else you'll get the complaint you are getting. You can fill Next for Leg 1, when data for Leg 2 has been defined in the table.

 

[Beauford]

Sorry for the late reply.
I have tried to no avail to arrive at the routing as the attachment, sorry I don't want to annoy anybody with my lack of knowledge, but I just don't seem to get it...as I said I am a newbie. If you have time (and the patience for me) would you have a look at the attachment?