Have you tried printing out the query you're executing and looking at it?
At least two of your mistakes would become apparent... "stoc k" as a column name, "$ wt" as a value...
$query = "INSERT INTO products(productID,category,productTitle,description,list,smallPic,bigPic,stoc k,manufacturer,weight) VALUES ('$sku','$categorie','$ti','$fdesc','$list','$small','$large','$qty','$mfg','$ wt'";
While it probably wouldn't cause a problem, are all these columns of type VARCHAR/TEXT? Numeric values shouldn't be enclosed in quotes as all your values are.