Urgent Help Needed ! TempTable Doesn't Store Any Data

Hi group,

I don't know what I should try next, all of my tries have been without results in this case. I just wanted to create a temporary table, then insert one row into it and then use this row to compare if this row exists in another table or not. This is my script:
------------------------
CREATE PROCEDURE imp_Tippimport (@TGName char(33)) AS

BEGIN

CREATE TABLE #tTippgeber (
TGName2 char(33)
)

INSERT INTO #tTippgeber (TGName2)
VALUES (@TGName)
*** see below ***

IF NOT exists (select TGName FROM Tippgeber WHERE TGName = @TGName)

INSERT INTO Tippgeber SELECT TGName2 FROM #tTippgeber
/* SELECT * INTO Tippgeber FROM #tTippgeber */

ELSE

UPDATE Tippgeber SET
TGName = t.TGName2
FROM #tTippgeber AS t, Tippgeber
WHERE TGName = t.TGName2

END
GO

I also created a cursor and used a fetch in to a veriable in the line with the stars to see the value of TGName2 but it was NULL.

Any ideas ?!

Thanks for any help !!

Sascha