Sometimes while using class files in we will face the situation where we want to place both Vb and Cs class files.The simple solution is:

1) First make two folders in App_code with foldernames as 1)CSCode 2)VBCode

2) Modify the Web.conig with following code:

    <compilation debug="false">
        <add directoryName="VBCode" />
        <add directoryName="CSCode" />

Thats all.....