Error reporting The SELECT statement includes a reserved word?

Question

In C # .net when running an SQL query to get access data with an error The SELECT statement includes a reserved word or an argument name that is misspelled or missing, or the punctuation is incorrect, the problem is incorrect:

SELECT COUNT (MAPB) AS Count
FROM TABNHANVIEN
WHERE (HIENAN = 'True') AND (MAPB = 3)
GROUP BY MAPB;

But I copy this query directly to the access sql query to run normally, with no error, I run another query in C # .Net running normally, no error like this message, you know what is wrong is not?