File Size of the Filename returned from FM

Dear Friends,

  I have used the Function module SO_SPLIT_FILE_AND_PATH

  and passed into this FM the file path( '\\Client\C$\Users\Desktop\Test.pdf)

  it returend me the file name as Test.PDF

   now my requiremnt is to find the size  Test.PDF. which iam unable to get .

However iam not able get the size of the fiename (Test.PDF)  from above .

so i went to second method based on the SCN search i have done in the  the below way.

v_fname = '\\Client\C$\Users\Desktop\Test.pdf

        CALL METHOD cl_gui_frontend_services=>file_get_size

          EXPORTING

            file_name = v_fname

          IMPORTING

            file_size = gv_filesize.


        if sy-subrc eq 0.

          CALL METHOD cl_gui_cfw=>flush.

        endif.

iam getting value in gv_filesize as -1.

Could any one correct me where exactly i went wrong .

Thanks & Regards

syamala