My HP Deskjet 2050 J510 can NOT scan for my MBA.

My HP Deskjet 2050 J510 can NOT scan with my MBA. It could not print before I download the printer driver as described in the below link...

http://support.apple.com/kb/HT4670

After install the printer drive...

Now the printing function works fine, but the scan function won't work. Could anyone give me a suggestion to make both printing and scanner functions work?

Thank you

Bill