Counting in Dreamweaver with PHP and mySQL

[eraserr]

I get error:
"Warning: Supplied argument is not a valid MySQL result resource in.."

But I don't think there should be any error in code below.

Thank you for your help!

thread
******
id
topic
title


SOURCE:
$my_sql_string_count = "
SELECT COUNT(id) AS counter
FROM thread
WHERE topic = 1
";

$result_count = mysql_query ($my_sql_string_count);
$row_count = mysql_fetch_row ($result_count);
echo $row_count["counter"];

 

[eraserr]

Sorry for bothering you, I forgot something so obvious, that I did't find problem so soon. I forgot to include connection to base before sql_string...