Hi Ludek Uher,
Thank you for your useful reply. I am really sorry for the useless details I write
Actually, that's because I don't know more. And its my first time i worked with server
usually i only do programming and and upload my files if any i get error in the server the server administrator solve it.
this time i have to immigrate all my web apps to new server and i am the administrator.
about my issue.
in fact my web app was work on my development system and also in the old production server
and I mean by application pool v2 that my web app framework is .net 3.5
and my server platform is 64
so i install crystal report 64
crystal report run time engine version is 13.0.9.1312
this all info I know and the problem in my code exactly happen when I assign the Data Set as Data Source to my crystal report.
otherwise when I do not use Data Set as Data source to Crystal report it works