Error I dont understand

["teacherweeks" <teacherweeks@xxxxxxxxx>]

I am getting an error on a line of code that I don't understand and I
am hoping that someone can explain it to me. I will include the error
and line of code that it is telling me is the problem.

Weeks

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL
result resource. 

while($row = mysql_fetch_array($result)){
// Increment the total cost of all items
$totalCost += ($row["qty"] * $row["itemPrice"]);