Failed to bind SQL tables

Hello

Well, I have a problem when i try to bind two tables

I have next tables

TABLE 1                                                                 TABLE 2
Name       TYPE                                                 Name               TYPE
mes              float                                                      mes                     float
venta      float                                                      VolumeShare       float
                                                                      MoneyShare        float

I make the bind on my Diagram binding mes(T1) with mes (t2)
But show the next message:


"Cannot insert the value NULL into column 'diagram_id', table 'Sicom.dbo.sysdiagrams'; column does not allow nulls. INSERT fails.
The statement has been terminated.
The 'sp_creatediagram' procedure attempted to return a status of NULL, which is not allowed. A status of 0 will be returned instead. (.Net SqlClient Data Provider)"