asp.net with oracle 10G not working with oracle 11G client

Hi,

I have build and published application on my local machine using oracle 10 G and vs2010 (asp.net/C#) everything works fine but I copied same code to web server its not working. web server have oracle 11G and vs2010. 

1 - I got error "File or assembly name Oracle.DataAccess", or one of its dependency was not found' then I added Oracle.DataAcces.dll in bin folder and I did build/publish and copied on web server and now I am getting this error "Unable to load DLL 'OraOps10.dll".

Could you please suggest how can I make application which works on both10G or 11G.

Thanks.