Find relationships in my DB

Hi there,
I tried to create a database diagram but when saving it, I got an error and the diagram was not saved.
I then tried to re-create the diagram (starting with only 2 of the tables) - however, I got then got this error.

'STU_Student' table saved successfully

  • Unable to create relationship 'FK_STU_MOVEMENT_STU_Student'.
    The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK_STU_MOVEMENT_STU_Student". The conflict occurred in database "Demo", table "dbo.STU_Student", column 'ID_Student'.

Problem is that I cannot see where the relationship (FK_STU_MOVEMENT_STU_Student) is defined in the database.
I have looked in each of the folder in the db and the FK is not listed anywhere.
I thought it would be in either the 'KEYS' or 'CONSTRAINTS' folder ?

Also: an "ALTER TABLE...DROP CONSTRAINT" tells me that the constrain does not exist.
How do I find the constraint so that I can delete it/recreate it.

check out the index "folder".