Hi,  evreryone:

When I use  VS 2012  to create report with reportviwer 11.0, I  meet a  problem about Multiple report viewers on one page. But when we use reportviwer 9.0   ，It is Ok. 

It is the second report doesn't display. It  prompt  an error  like the picture below. 

   I solve this problem by setting the AsyncRendering property of ReportViewer  false . It works Ok.  Maybe  it will help you in the future .

    You can also see it on msdn social:Multiple report viewers on one page issue. I answer the issue.

Thank you .