Question about site penalization

Hi,

I have a site with old domain and good ranking with some keywords,but in last panda update my site lost its ranking even with its own domain name keyword.

I have also requested to Google for reconsidering my site after removing all OBL but they replied that your site does not meet our quality terms.I do not know now whats wrong with my site even with unique contents.

Is there any way to check site weakness online then please let me know.

Looking for your best suggestion specially from experienced webmasters.

Regards
Globex

you are going to need to supply a lot more details