Insert And Update Unicode

nsert and Update Unicode
Below I write some line of my SP
But I does not write Unicode data to table, it writes like ????????
How can avoid this problem


SP header:

CREATE PROCEDURE ltrsp_AddEditUnit
@UnitID char(4),
@UnitName nvarchar(20),
@UtrID int

Insert:

INSERT INTO ltrtb_Unit (UnitID,UnitName,UtrID) VALUES (@UnitID,@UnitName,@UtrID)

Update:
---
UPDATE
ltrtb_Unit
SET
UnitName=@UnitName,UtrID=@UtrID

WHERE
UnitID=@UnitID