Excel file to internal table

Hi everybody!

I am using the function

CALL FUNCTION 'GUI_UPLOAD'

EXPORTING

filename = d_file

filetype = 'ASC'

has_field_separator = 'X'

TABLES

data_tab = it_file.

To fill the internal table it_file. The string d_file, contains the directory of an excel file. This is not working. But if I load a '.txt' file instead, it works! why??

Do you know any other function to use?

thanks a lot!

Regards,

Reyes.