This used to work and suddenly it does not work in IE.

Here's the function
function pdfWindow(loc)
  if(loc == "#RefQuide") {
     location.href = loc;
  } else {
     // The window attributes
     var window_attribs = "height=650,width=850,resizable=yes,scrollbars=yes";,"PDF",window_attribs);
Here's part of the HTML
<form name="myForm">
<select name="hypercomList">
<option value="/CWRWeb/pdf/HypercomT4000.pdf">Hypercom T4000 </option>
<option value="/CWRWeb/pdf/HypercomT4100.pdf">Hypercom T4100 </option>					
<input type="button" value="Go!" onclick="pdfWindow(myForm.hypercomList.options[myForm.hypercomList.selectedIndex].value)">
Any ideas why it would open a blank page instead of the PDF? Works ok in FF.