Order By Returning No Rows

[Damian Taylor]

Hi guys,
I'm still pretty new to MySQL so would like a second opinion on this one!
Can anyone tell me if this is a bug in MySQL or just an error in my SQL?
I have a select statement that uses the order by clause. When I run the statement, it returns no rows which I think is incorrect.
If I remove the order by clause, it returns the rows I would expect.

I know this SQL won't mean much to anyone else give you don't know what the table structures are, but here is the statement I'm running that returns no rows:

SELECT DISTINCT p.products_image, pd.products_name, m.manufacturers_name, p.products_model, p.products_quantity, p.products_id, p.products_type, p.master_categories_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, pd.products_description, IF(s.status = 1, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status =1, s.specials_new_products_price, p.products_price) as final_price, p.products_sort_order, p.product_is_call, p.product_is_always_free_shipping, p.products_qty_box_status
FROM products p
LEFT JOIN specials s on p.products_id = s.products_id
LEFT JOIN products_description pd on p.products_id = pd.products_id
LEFT JOIN manufacturers m on p.manufacturers_id = m.manufacturers_id
JOIN products_to_categories p2c on p.products_id = p2c.products_id
JOIN products_attributes p2a on p.products_id = p2a.products_id
JOIN products_options po on p2a.options_id = po.products_options_id
JOIN products_options_values pov on p2a.options_values_id = pov.products_options_values_id
WHERE p.products_status = 1
and pd.language_id = '1'
and p2c.categories_id = '17'
GROUP BY p.products_id
HAVING(FIND_IN_SET('Sizes80x32', GROUP_CONCAT(CONCAT(REPLACE(po.products_options_name, ' ', ''), pov.products_options_values_name))))
order by p.products_sort_order, pd.products_name
limit 12

If I just remove the 'order by', it works perfectly:

SELECT DISTINCT p.products_image, pd.products_name, m.manufacturers_name, p.products_model, p.products_quantity, p.products_id, p.products_type, p.master_categories_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, pd.products_description, IF(s.status = 1, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status =1, s.specials_new_products_price, p.products_price) as final_price, p.products_sort_order, p.product_is_call, p.product_is_always_free_shipping, p.products_qty_box_status
FROM products p
LEFT JOIN specials s on p.products_id = s.products_id
LEFT JOIN products_description pd on p.products_id = pd.products_id
LEFT JOIN manufacturers m on p.manufacturers_id = m.manufacturers_id
JOIN products_to_categories p2c on p.products_id = p2c.products_id
JOIN products_attributes p2a on p.products_id = p2a.products_id
JOIN products_options po on p2a.options_id = po.products_options_id
JOIN products_options_values pov on p2a.options_values_id = pov.products_options_values_id
WHERE p.products_status = 1
and pd.language_id = '1'
and p2c.categories_id = '17'
GROUP BY p.products_id
HAVING(FIND_IN_SET('Sizes80x32', GROUP_CONCAT(CONCAT(REPLACE(po.products_options_name, ' ', ''), pov.products_options_values_name))))
limit 12

Is this a known MySQL issue?

Thanks for looking!