User Import doesn't update profile_values table

Hi when I import new users, user_import doesn't insert values to profile_values table. The following conditional statement seems to be the problem

if (empty($exists) && $exists != '') {
    db_query("INSERT INTO {profile_values} (fid,uid,value) VALUES(%d,%d,'%s')", $field->fid, $uid, $value);
}

The second condition ($exists != '') always contradicts the first condition ie. when the first condition is true, the second condition is always false hence the insert statement never get invoked.