Unofficial File Manager PHP PDF problem

For some reason the first time I upload a PDF file I get an error: "Invalid XML response from connector"
I traced it down to the GetUploadProgressCallback function. And it looks like var oNode = fckXml.SelectSingleNode( 'Connector/CurrentFolder' ) ; is being set to null whenever you upload a PDF. The second time around you don't get the error message because warned has been set to true. The PDF file still uploads correctly. XLS and DOC files don't give this error and I don't get this error when I do the upload on my IIS box, only my Linux shared server.

function GetUploadProgressCallback( fckXml ) {
// Get the current folder path.

if (!uploading) return false;

var oNode = fckXml.SelectSingleNode( 'Connector/CurrentFolder' ) ;
if (oNode==null) { alert("Invalid XML response from connector.(0)");
if(!warned) { alert("Invalid XML response from connector.(1)"); warned=true; } return false; }