Receving error with no description

I have designed quite a few reports over the past few weeks, and today I received the following error:

An error occured during local report processing.
The definition of the report /Discharge7.rdl is invalid.
Exception of type: 'Microsoft.ReportingServices.ReportProcessing.ReportProcessingException' was thrown.

I've never seen this error before. I've gotten errors with typos in names of fields in my expressions, but I've never gotten an error on the 40 someodd other forms I have.

Does anyone know what could be causing this?

Did u tried to preview this report before uploading it to the server, the error says that is not definned correctly, so the report must be bad, when you make a preview on the reporting services it will show you the detailed errors.

|||You can also look at the logs for more detailed error messages. These are located here on a default installation: C:\Program Files\Microsoft SQL Server\MSSQL\Reporting Services\LogFiles\

For more information about the various Reporting Services log files:
http://msdn2.microsoft.com/en-us/library/ms157403.aspx|||This was while I was previewing it in Visual Studio in the report designer. I haven't published it to the server yet.