Custom List Sorts Out of Order

In excel 2010 (on a W7 64-bit machine), I have created the following custom list:

Benzene
Toluene
Ethylbenzene
Total Xylenes
MTBE
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Chrysene
Dibenz(a,h)anthracene
Indeno(1,2,3-cd)pyrene
Naphthalene

Problem is, when I select a range to sort, the results are out of order, like this (the last 3 entries are out of order):

Benzene
Toluene
Ethylbenzene
Total Xylenes
MTBE
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Chrysene
Naphthalene
Dibenz(a,h)anthracene
Indeno(1,2,3-cd)pyrene

Odd thing is, when I go to the custom list dialogue box & highlight my custom list, the list is displayed in the correct order in the "List Entries" window. Even more odd, is if I type the 1st list entry (i.e. benzene) in a cell and drag down, the list will auto fill correctly.

I have tried deleting the list, restarting excel, and recreating the list to no avail. There are no other custom lists (other than the 4 default excel lists) displayed in the custom list dialogue.

Does anyone have any insight as to how I could sort (HA - pun!) this out?

Thanks in advance,

Lucas

Andy, thank you for the heads up with respect to the commas as they indeed were the culprits. In order to maintain both the auto fill and sorting functionality, I had to create two custom lists: one custom list where the commas are replaced with spaces and one custom list with commas. The custom list with commas gives me my desired auto fill; however, I had to make sure that when creating the two custom lists, the custom list with commas was created second. This was necessary as apparently when there are two custom lists that start with the same word, the auto fill text comes from the bottom of the two lists.

With respect to sorting, I will use a helper column as you indicated - the helper column will duplicate the text in the adjacent column; however, all commas will be replaced with spaces. Then, after selecting my entire range (including the helper column) I will sort on the helper column using the custom sort order list where the commas were replaced with spaces. Once complete, the helper column will be deleted.

Thanks again,

Lucas