页面加载时出现这个错误：

Could not load file or assembly 'Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.

　　下载这个文件安装即可：

　　Microsoft Report Viewer 2010 Redistributable Package