Error when open multiple XML documents

When open one generated xml document, below method works.

But when add it in the loop, open several xml at one time, the xml files can not be opened.

Can anyone helps on this> Thanks very much.

cl_wd_runtime_services=>attach_file_to_response(

EXPORTING

i_filename = 'test.xml'

i_content = lv_xfile

i_mime_type = 'application/xml' ).