problem with u2lcom.dll

hi

i use from crystal report 10

and i in this line :

 oStream = (System.IO.MemoryStream)
         a.ExportToStream(
         CrystalDecisions.Shared.ExportFormatType.PortableDocFormat);

get this erro :

The Visual Basic UFL that implements this function is missing (or U2lcom.dll is missing).

please help me

it's urgent

thanks