One to one relationship failing in entity framework code first

I am trying to build a One to one relationship EF v4.1 Code first. This is my code:

public class System
{
    [Key, ForeignKey("Station") ] 
    public int Id { get; set; }

    [DisplayName("Last Polled")]
    public DateTime? LastPolledOn { get; set; }

    public virtual Station Station { get; set; }
}

public class Station
{
    public int I开发者_运维技巧d { get; set; }               
    public int Status { get; set; }

    public string FullName
    {
        get
        {
            return StoreNumber + " - " + StoreName;
        }
    }

    public virtual System System{ get; set; }        
}

This works fine but when I delete Station, I get cascade delete error:

"The primary key value cannot be deleted because references to this key still exist. [ Foreign key constraint name = System_Station ]"}"

What should I do to resolve this?

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As the error message tells you, there is still a foreign key relation to the Station, so eighter use cascaded delete or delete the relating rows in System first.

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The primary key of System is also the foreign key to Station. If you delete Station you need to delete System first. You can also use cascaded delete.