Because it sounds like the file you got from Voyager is in the wrong format. It is way easier to ask them to send you the file again, in the correct format, than it is to do any manual manipulation to what they sent earlier.
The link I provided in my first message is their request form. On page 2 of filling that out, it asks what format you want the file to be in. Assuming you’re trying to import the file to CoinTracker, just choose the CoinTracker output format. When they send your transactions in the CoinTracker format, it’ll load just fine.