I was adding few XsltListViewWebPart web parts programatically on a web part page. But the web parts were not getting added in proper order. Following is the code which adds XsltListViewWebPart to page.
Here is how this code was called to add there web parts on a page in the same zone named "ContentZone":
But "Other Contacts" was getting added before "External Contacts". After some hit and trial I changed the zone index to start from 1 rather than zero and it worked. Here is the updated code: