Thank you ieee488 for your valuable reply, I re-installed the drivers according to your suggestion but no improvement, Bluetooth issue is still there.
Check all drivers at Dell ftp server.
i recommend latest driver version as well you need to check the WiFi/Bluetooth model number, to do so, enter your service tag at Dell support page and see Original System configuration.
if this didn't help, i recommend to contact Dell support by email or chat and find out that info directly.
i noticed that Bluetooth share same file together with WiFi adapter, though in your picture, Bluetooth is installed but WiFi driver isnt!