error in converting tiff file to pdf file

when i convert tiff file to pdf in debug mode it converted successfully but when i host it on localhost it didn't convert and throw an exception:

Cann't make pdf files. Try again.System.Runtime.InteropServices.COMException (0x80040154): Retrieving the COM class facto开发者_高级运维ry for component with CLSID {71DBCBF1-587B-42E4-9B30-74B80F4AA70F} failed.

why it happened. please give any suggestion Thanks

It would appear that the DLL you are referencing is not registered: http://support.microsoft.com/kb/201191

Check that the tool you are using is correctly installed, if it is a standalone DLL you may need to register it manualy (i.e. use regsvr32.exe).