Price in layered navigation dropdown not in sequence

Question

I am getting issue in price dropdown in layered navigation. It is displaying as below

But it should appear in order like
10 - 20
20 - 30
30 - 40
40 - 50
But as you can see, it is not at all in order and I am not getting from where I should start debugging.
Please let me know if anybody face this type of issue earlier and give some guidance in fixing this and what can be the issue?
Any help will be appreciated.

Answer 1

The price filter layer is generated here: Mage_Catalog_Model_Layer_Filter_Price

I would assume the error occurs here: \Mage_Catalog_Model_Layer_Filter_Price::_getItemsData but I have no idea. Wherever it happens, this class should be the right one.