problem reading excel file from application server

Hi expert ,

When I upload file by using  binary mode in cg3z tranjection and try to read the file by this bellow code it can not read file and it will give dump

( A character set conversion is not possible.) .but when i upload exact file by using ascii mode i can read this file .

I think may be bold part of coding is any wrong .So can anyone help me what is the exact problem ?

Code:-

OPEN DATASET ofile FORINPUTINTEXTMODEENCODINGDEFAULT.
     DO.
       READDATASET ofile INTO wa_tab .
       IF sy-subrc EQ0.
         APPEND wa_tab TO it_tab .
       ELSE .
         CLOSEDATASET ofile.
       ENDIF.
     ENDDO .
closeDATASET ofile .

Thanks & Regards

Rajesh