Finally after fighting with this issue 3 days i solved it.
here is what i did: 1) I was publishing the code from 32 bit machine windows 8 2) my server was windows server 2008 R2 64bit machine.
=>I enabled 32bit applications from iis options which never solved my problem as per googling then i => set "Load User profile" which again never solved my problem. =>then somebody told me give full rights to abcPDF and abcGeco dlls on your server that also never worked.
Then i finally, compiled my code from 64bit machine OR i copied 64bit ABCpdf & ABCGeco dll files from bin folder into my published folder that finally worked.