Problem with Upgrade 4.6C to ECC 6.0

Hi Experts,

after the upgrade from relase 4.6C to ECC 6.0, some Function Modules have the following error:

"In EXPORT/IMPORT and ASSERT... FIELDS, "IS_OUTPUTDATA" cannot be a reference nor can it contain references..." where IS_OUTPUTDATA is a exporting parameter (not table) and it is declared type SSFCRESCL (standard structure):

*" IMPORTING

*" VALUE(VBELN) TYPE VBELN

*" VALUE(KUNNR) TYPE KUNNR

*" EXPORTING

*" <b>VALUE(IS_OUTPUTDATA) TYPE SSFCRESCL</b>

*" VALUE(TOTBYTES) TYPE I

*" VALUE(PDF_BIN) TYPE XSTRING

How can I resolve the problem?

Thanks a lot and sorry for my bad english.

Umberto