Error when accessing Active directory - Asp.Net web application

Hi All,
I'm trying to pull user details/validating credentials against active directory and getting the below error when i run the code in Web application and i'm good with console application.I've verified the active directory team and they conveyed that service ID has read only access...Do i need to modify anything with the code/IIS settings to get out from the error.Please help
System.Runtime.InteropServices.COMException (0x80005000): Unknown error (0x80005000)    at System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail)    at System.DirectoryServices.DirectoryEntry.Bind()    at System.DirectoryServices.DirectoryEntry.get_AdsObject()    at System.DirectoryServices.DirectorySearcher.FindAll(Boolean findMoreThanOne)    at System.DirectoryServices.DirectorySearcher.FindOne()