Default [Q] Kindle paperwhite firmware update problem

Hello everybody
I recently check out amazon for its new firmware update for kindle paperwhite 1st generation: 5.4.4.2
amazon.com/gp/help/customer/display.html/ref=hp_left_sib?ie=UTF8&nodeId=201064850

I followed the instruction on this page :
amazon.com/gp/help/customer/display.html?nodeId=201177270

But the option of "Update your Kindle" is still grayed out... and i dont know what happens when I transfer the downloaded file (.bin) immediately to my kindle drive (according to instruction) and reconnect the device the transferred file is automatically deleted!!!
by the way my current firmware version is 5.4.3.2.
any help please?
thanks in advance