Pepakura "Cannot load file of specified type"

[Roughosing]

I want to Build a full set of Mark VI armor , and i downloaded the entire set of 4shared.com , and when I try and Drag and Drop the .pdo files into pepakura , a little box pops up saying "Cannot load file of specified type" and it wont let me use the file , I have no idea what to do and I am stuck in the dark about this . Please could someone help!!( I did download a file from Vrogy.net Mirror and it work fine , so im not sure what the problem is !!)