want do combine an update with an join
update in tabel artikel a value from the entrys of the table inm

updates only the first entry (why?):
UPDATE artikel set kalk_fakto = inm.ek WHERE inm.hstnummer=artikel.art_bez2

brings me all i want but update?:
SELECT * from artikel INNER JOIN inm ON inm.hstnummer=artikel.art_bez2

with join statement it does not work at all (error):
UPDATE artikel SET kalk_fakto = inm.ek FROM artikel INNER JOIN inm ON inm.hstnummer = artikel.art_bez2

can smb. help me?