Link Arrows to Userdefined Objects

SBO2005A should support Linkedbuttons (Yellow Arrows) to UDOs, but I can't get this to work for the 3 cases... Anyone got this working:

1.

LinkedButtons in Grids

The grids EditTextColumn just have the LinkedObjectType. If i type the UDO's UID here linkedbuttons does not appear

grid.Columns.Item("DocNum").Type = BoGridColumnType.gct_EditText;
EditTextColumn col = (EditTextColumn)grid.Columns.Item("DocNum"];
col.LinkedObjectType = "UDO_UID";

2.

Normal linked buttons

Item i = oForm.Items.Add(ItemUID,BoFormItemTypes.it_LINKED_BUTTON);
i.LinkTo = "LinkedItemUID";
LinkedButton lb = (LinkedButton)i.Specific;
lb.LinkedObject = BoLinkedObject.lf_UserDefinedObject;
lb.LinkedObjectType = "LinkedObjectType"; //The UDO

3.

On normal matrix

LinkedButton lb = (LinkedButton)oColumn.ExtendedObject;
lb.LinkedObject = LinkedObject;
lb.LinkedObjectType = "UDOUID";

Can anyone tell what i'm doing wrong....