Fax Cover page fray out HP MFP 500

Hi all,

I have installed HP_MFP_Sendfax300 on windows 7, 64 bit for HP MFP 525. I can send fax sucessfully without cover page.  However, when I try to send a document as fax; and select HP MFP Send fax as proper device in print option, the cover page gray out and I don't have access to "Include With Fax" section. in contrast, when I go  "Devices and printers" for priting test page, I can check mark the Cover page section and have  access to "Include with Fax" .

please advice.

Thank you,

Kam