具体提示：
Could not load file or assembly ‘Oracle.DataAccess‘ or one of its dependencies. 试图加载格式不正确的程序。
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.BadImageFormatException: Could not load file or assembly ‘Oracle.DataAccess‘ or one of its dependencies. 试图加载格式不正确的程序。
解决方案：
因为这个Oracle.DataAccess.dll为32位，所以应用程序不兼容造成此种错误。具体解决方法如下。
在IIS应用程序池中，启用32位应用程序设置为true即可。
iis配置问题报错 -- Could not load file or assembly 'Oracle.DataAccess' or one of its dependencies
原文：http://www.cnblogs.com/arxive/p/7251629.html