Establishing InterUnit Transfers Error

Good afternoon,

I am trying to source an Inventory Business Unit from another Inventory BU, but i'm getting a sourcing error:

"InterUnit Inventory demand cannot be created because InterUnit relationship does not exist for one of the Inventory business units in the distribution network. Please examine the inventory business unit that is on the staged distribution, and ensure that a InterUnit relationship exists for that Inventory business unit and every Inventory business unit in the distribution network. "

I have my Dist Network setup, the Ship to identified, the Transfer Attribute Details and the InterUnit      Transfers Accounting (Who owns what BU's).