updating city name from another table's city name

Hi everyone,
I have 2 tables: t1 and t2. Each table contains a "city" column. In t1 some city names have additional remark closed between parentheses eg
(mycity (wonderful)) and i want city names in t2 to have those parentheses added. I do it as follows:
[query]
UPDATE b
SET
b.city=a.city
FROM
t1 AS a LEFT JOIN t2 AS b
ON
SUBSTRING(a.city,1,CHARINDEX('(',a.city)-1)=b.city
WHERE
a.city LIKE '%(%'
[/query]
Running the above code i got NULL to all city names in t2 !
At the othe hand when i run:

Code:

SELECT
a.city,
b.city
FROM
t1 AS a LEFT JOIN t2 AS b
ON
SUBSTRING(a.city,1,CHARINDEX('(',a.city)-1)=b.city
WHERE
a.city LIKE '%(%'

I get the "parenthesesed" cities side by side with the "non parenthesesed" cities.
Can anyone solv that mystery ?
Thanks