Lazy Load in Entity Framework 3.5

Hi ,

      I want to check null control in entity framework which uses 3.5 version.  I have  an example like below.

       if(!ctx.Order.UnitReference.IsLoaded)
          ctx.Order.UnitReference.Load()

     Now , I have multiciplity  1 to Many in this situation   it gives error whe Unit table does not have relational record  because it excepts the record if i change mutliciplity 0 to 1  it works well. My Problem is i dont want to change mulitipclity, it become 1 to Many, but i can check Load() method  is null ,if  it is null i do somejob ..

   How can i do?

   Thanks

  Best Regards...