Почему не работает UPDATE c#?

UPDATE products SET manager = (
SELECT user FROM brandUsers WHERE firstCom IS NOT NULL AND prodBrand = brandUsers.brand AND firstCom = brandUsers.user
) WHERE manager IS NULL AND firstCom IS NOT NULL;

using (SQLiteConnection connection = new SQLiteConnection(string.Format("Data Source={0};", dbPath)))
{
	string sqlCom = $@"UPDATE products SET manager = (
                SELECT user FROM brandUsers WHERE firstCom IS NOT NULL AND prodBrand = brandUsers.brand AND 
                firstCom = brandUsers.user
		) WHERE manager IS NULL AND firstCom IS NOT NULL";
		
	connection.Open();
	
	SQLiteCommand command = new SQLiteCommand(sqlCom, connection);
	try
	{
		command.ExecuteNonQuery();
		connection.Close();
		return true;
	}
	catch
	{
		File.AppendAllText(Environment.CurrentDirectory + @"\SQLError.txt", DateTime.Now.ToString() + "\t" + sqlCom + Environment.NewLine);
		connection.Close();
		return false;
	}              
}