mysql.NullTime有效但是sql.NullTime不起作用

Question

I have a table named package_redeem and a field called expire_at with type TIMESTAMP

my Go method to retrieve value is as follow

// RetrieveRedeemRecord will Retrieve a RedeemCode Record by Code; R of CRUD
func RetrieveRedeemRecord(code string) (anyError error) {

    var thisWorks mysql.NullTime
    var thisOneNotWork sql.NullTime

    stmtStr := `SELECT expire_at FROM package_redeem WHERE code=?`
    anyError = dbhelper.GetDB().QueryRow(stmtStr, code).Scan(&thisOneNotWork)
    switch anyError {
    case nil:
    case sql.ErrNoRows:
        log.Println("no row found with ", code)
    default:
        log.Panic("errRow(s) ", anyError.Error())
    }

    return anyError
}

Weird thing is that using type sql.NullTime will panic!

panic: errRow(s) sql: Scan error on column index 5, name "updated_at": unsupported Scan, storing driver.Value type []uint8 into type *time.Time [recovered]
            panic: errRow(s) sql: Scan error on column index 5, name "updated_at": unsupported Scan, storing driver.Value type []uint8 into type *time.Time

But using type mysql.NullTime would work, I thought since Go1.3 that mysql.NullTime is just sql.NullTime. Am I missing something here?