ERROR WHILE CALLING SSF_KRN_VERIFY with return code 6

HI experts,

we have a requirement to verify digital certificate while printing invoice. we have configured  certificate in TRUST MANAGER and PSE is generated.

Below is my code

CALL FUNCTION 'GUI_UPLOAD'
   EXPORTING
     FILENAME                      = 'C:\test\pse\cer.pse'
     FILETYPE                      = 'BIN'
*   HAS_FIELD_SEPARATOR           = ' '
*   HEADER_LENGTH                 = 0
*   READ_BY_LINE                  = 'X'
*   DAT_MODE                      = ' '
*   CODEPAGE                      = ' '
*   IGNORE_CERR                   = ABAP_TRUE
*   REPLACEMENT                   = '#'
*   CHECK_BOM                     = ' '
*   VIRUS_SCAN_PROFILE            =
*   NO_AUTH_CHECK                 = ' '
* IMPORTING
*   FILELENGTH                    =
*   HEADER                        =
   TABLES
     DATA_TAB                      = it_data
* EXCEPTIONS
*   FILE_OPEN_ERROR               = 1
*   FILE_READ_ERROR               = 2
*   NO_BATCH                      = 3
*   GUI_REFUSE_FILETRANSFER       = 4
*   INVALID_TYPE                  = 5
*   NO_AUTHORITY                  = 6
*   UNKNOWN_ERROR                 = 7
*   BAD_DATA_FORMAT               = 8
*   HEADER_NOT_ALLOWED            = 9
*   SEPARATOR_NOT_ALLOWED         = 10
*   HEADER_TOO_LONG               = 11
*   UNKNOWN_DP_ERROR              = 12
*   ACCESS_DENIED                 = 13
*   DP_OUT_OF_MEMORY              = 14
*   DISK_FULL                     = 15
*   DP_TIMEOUT                    = 16
*   OTHERS                        = 17
           .
IF SY-SUBRC <> 0.
* Implement suitable error handling here
ENDIF.

DATA: l_SSFTOOLKIT LIKE SSFPARMS-SSFTOOLKIT,
l_SSFFORMAT LIKE SSFPARMS-SSFFORMAT.
data:l_pab TYPE ssfparms-pab,
l_pabpw TYPE ssfparms-pabpw,
signer_info_tab TYPE ssfinfo OCCURS 0,
output_data_l type SSFPARMS-OUTDATALEN,
l_crc type SSFPARMS-SSFCRC .

CALL FUNCTION 'SSF_GET_PARAMETER'
   EXPORTING
     APPLICATION             = 'ZMYAPP'
   IMPORTING
     SSFTOOLKIT              = l_SSFTOOLKIT
     STR_FORMAT              = l_SSFFORMAT
     str_pab                 = l_pab
     str_pab_password        = l_pabpw
   EXCEPTIONS
     ssf_parameter_not_found = 1
     OTHERS                  = 2.

CALL FUNCTION 'SSF_KRN_VERIFY'
   EXPORTING
     SSFTOOLKIT                   = l_SSFTOOLKIT
     STR_FORMAT                   = l_SSFFORMAT
     b_inc_certs                  = 'X'
*   b_inenc                      = 'X'
     B_OUTDEC                     = 'X'
*   IO_SPEC                      = 'T'
     ostr_signed_data_l           = '1024'"datalen "signed_data_l
*   ostr_input_data_l            = “detached only
     str_pab                      = l_pab
     str_pab_password             = l_pabpw
   IMPORTING
     OSTR_OUTPUT_DATA_L           = output_data_l
     CRC                          = l_crc
   TABLES
     ostr_signed_data             = it_data
*   ostr_input_data              = “ detached only
     signer_result_list           = signer_info_tab
     ostr_output_data             = out_data
   EXCEPTIONS
     ssf_krn_error                = 1
     ssf_krn_noop                 = 2
     ssf_krn_nomemory             = 3
     ssf_krn_opinv                = 4
     ssf_krn_nossflib             = 5
     ssf_krn_input_data_error     = 6
     ssf_krn_invalid_par          = 7
     ssf_krn_invalid_parlen       = 8
     ssf_fb_input_parameter_error = 9
     OTHERS                       = 10.

IF SY-SUBRC <> 0 .
* Implement suitable error handling here
MESSAGE 'FAILED' TYPE 'I'.
else.
   if l_crc <> 0.
     MESSAGE 'FAILED' TYPE 'I'.
   else.
  MESSAGE 'VERIFIED' TYPE 'S'.
  endif.
ENDIF.