[nico_swd]

Because you use $message in the second source string. Use $test there.

PHP Code:

$test = @str_replace("{username}", $vbulletin->userinfo['username'], $message);
$test = @str_replace("{userid}", $vbulletin->userinfo['userid'], $test); 


$message remains the same after the first replacement and $test gets overwritten with the second replacement.