Getting blank page

Smartclient version: 8.2 , 10.0
Browser: Mozilla, IE

I have a use case for downloading a file from a list grid.Its working fine in happy path but i am getting blank page if there is an exception occurred.

var my_url = FGUtils.appendUniqueCsrfTokenToURL("./DownloadMailboxMessage.do", true) + "&messageId=" + record.messageId;
var prompt_msg = "Message Name" + "</B>&nbsp;&nbsp;&nbsp;" + record.messageName + "<BR><BR><B>" + "Message Path" + ":</B>&nbsp;" + record.mailboxPath + "</B>";
isc.confirm(prompt_msg,
function(value) {
if (value) {
var downloadMessageForm = isc.DynamicForm.create({
autoDraw:true,
action: my_url,
method: "POST"
});

downloadMessageForm.submitForm();

downloadFileResults_ListGrid.setData([]);
downloadFileResults_ListGrid.fetchData();
}
});
};

while calling submitForm() i am getting blank page if any exception occured.