Text of the error:
An error occurred during local report processing. The definition of the report 'Main Report' is invalid. The report definition is not valid.
Details: The report definition has an invalid target namespace
'http://schemas.microsoft.com/sqlserver/reporting/2008/01/reportdefinition' which cannot be upgraded.
I'm not getting to run any reports in my laptop . But it works perfectly well in my office system. Any help appreciated.
EDIT: Excluding and re including not working.
my "C:\Program Files(x86)\MSBuild\Microsoft\VisualStudio\v10.0\ReportingServices\Microsoft.ReportingServices.targets" file not changed. its version is 10.0.0
Edit: if you want to know why it dint work in the first place , go to reference and right click on microsoft.Reportviewer.Common and click view in object browser.Here you can see it was pointing towards version 9.0 which is not compatible(atleast in vs 10).
Changing the reference worked (from version 9.0 to 10.0). Right click on reference and add reference from C:\Program Files\Microsoft Visual Studio 10.0\ReportViewer and then add all dll given there(after removing report related dll from project reference).
All the comments given showed me the correct path. Posting this fairly simple answer for beginners like me .