将字符串转换为smalldatetime数据类型时转换失败

SELECT B.Value
FROM table1 A WITH (NOLOCK) 
INNER JOIN table2 B WITH (NOLOCK) ON A.id = B.id
WHERE
    A.Name = 'COMPLETED_AT' 
    AND CONVERT(smalldatetime, A.Value) < GETDATE() - 30
    AND B.Name = 'RESULT'
SELECT B.Value
FROM table1 A WITH (NOLOCK) 
INN