Delivery Slip and Invoice won't open in a new window

[sharkey]

When I click the Delivery Slip and Invoice they only download. It is not my browser settings as I have had tried and several computers. 

It's making me crazy I prefer to open and print.  I am NOT  programmer. Here is the code;
<a class="btn btn-default" href="index.php?controller=AdminPdf&token=a7e89c91c878dfe9fdb8d5c579424e3d&submitAction=generateDeliverySlipPDF&id_order=4081" target="_blank">

<i class="icon-truck"></i>

View delivery slip

</a>

 

​It has NOTHING to do with my browser configuration as other site's PDFs open just fine in a new tab. This is an issue on Chrome and Safari

 

 

Thank you