求救！php连接好ODBC之后无法查询！
$connect=odbc_connect("woody","woody","woody")
or die("Could not connect: " . odbc_error());
if($connect) printf ("Connected successfully");
$sql="select * from marks ";
$result=odbc_do($connect,$sql)or die("query failed");
$row=odbc_num_rows($result);
for($j=0;$j<20;$j++)
{ $fetch=odbc_fetch_array($result);
$mark[$j]=$fetch['mark'];
echo "$mark[$j]";}

运行后显示：
Connected successfully
Warning: odbc_do() [function.odbc-do]: SQL error: [Microsoft][ODBC SQL Server Driver][SQL Server]对象名 'marks' 无效。, SQL state S0002 in SQLExecDirect in c:\Inetpub\wwwroot\sx\include.php on line 28
query failed
是怎么回事啊？？？