C语言使用ODBC连接ACCESS数据库

SQLHENV henv = SQL_NULL_HENV;  //环境句柄
	SQLHDBC hdbc = SQL_NULL_HDBC; //odbc连接句柄
	SQLHSTMT hstmt = SQL_NULL_HSTMT; //语句句柄

	SQLRETURN retcode;
	SQLTCHAR connout[256];/**/
	SQLSMALLINT connout_len;
	SQLTCHAR select[] = _T("select * from user");
	//SQLTCHAR *connstr = CON_STR;
	SQLTCHAR connstr[] = _T("Driver={ Microsoft Access Driver(*.mdb, *.accdb) }; Dbq=D:\test.accdb;Uid=Admin;Pwd=;CharSet=gbk;");
	//SQLCHAR connstr[] = "Driver={Microsoft Access Driver (*.mdb, *.accdb)};UID=;PWD=;Dbq=D:\\PersonAL.mdb;CharSet=gbk;";

	//分配环境
	retcode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
	//设置环境属性
	retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3, 0);
	//分配链结
	retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
	//创建数据库链结
	//retcode = SQLDriverConnect()

	//设置连接属性 

	retcode = SQLSetConnectAttr(hdbc, SQL_LOGIN_TIMEOUT, (void*)LOGIN_TIMEOUT, 0);
	retcode = SQLDriverConnect(hdbc, NULL, connstr, SQL_NTS, connout, sizeof(connout),
		&connout_len, SQL_DRIVER_NOPROMPT);

为什么SQLDriverConnect连接总是失败啊？求帮忙，先谢谢了。