YafaRay Plug-in - reviewing for Yafaray 3.0

[tkbd]

micheus,I tested with the latest version you sent me yesterday.
The io-lib format should be correct, but I get the same error log as before.
Rendering failed even though no error should have occurred....

So , to do a comparative test , I made the data for latin name.
(All datas are not use unicode), and tried rending again.
A following error message output. Maybe this cause the errors.

Code:

Exporting  to: /Users/User/Desktop/yafaray_sample_data/okok/wpc_yafaray-1105-BQQLIQ.xml
for render to: //Users/User/Desktop/yafaray_sample_data/okok/with_tex_namee.png
Mesh w_Cue1: triangulating...done
Mesh w_Cue1: exporting...done
ERROR: Failed to export:
{'EXIT',{badarg,[{io_lib,format,
                         ["<background name=\"t\">",["x_ConstBackground"]],
                         [{file,"io_lib.erl"},{line,187}]},
                 {wpc_yafaray,print,3,[{file,"wpc_yafaray.erl"},{line,5846}]},
                 {wpc_yafaray,export_background,3,
                              [{file,"wpc_yafaray.erl"},{line,5117}]},
                 {wpc_yafaray,export,3,[{file,"wpc_yafaray.erl"},{line,3205}]},
                 {wpc_yafaray,'-do_export/4-fun-0-',3,
                              [{file,"wpc_yafaray.erl"},{line,697}]},
                 {wings_export,export,4,[{file,"wings_export.erl"},{line,40}]},
                 {wings_file,'-export_filename_1/2-fun-0-',3,
                             [{file,"wings_file.erl"},{line,97}]},
                 {wings_develop,time_command,2,
                                [{file,"wings_develop.erl"},{line,87}]},
                 {wings_plugin,command,3,
                               [{file,"wings_plugin.erl"},{line,147}]},
                 {wings,raw_command_1,3,[{file,"wings.erl"},{line,644}]},
                 {wings,raw_command,4,[{file,"wings.erl"},{line,641}]},
                 {wings_wm,handle_event,3,[{file,"wings_wm.erl"},{line,1030}]},
                 {wings_wm,send_event,2,[{file,"wings_wm.erl"},{line,996}]},
                 {wings_wm,do_dispatch,2,[{file,"wings_wm.erl"},{line,888}]},
                 {wings_wm,dispatch_event,1,
                           [{file,"wings_wm.erl"},{line,797}]},
                 {wings_wm,get_and_dispatch,0,
                           [{file,"wings_wm.erl"},{line,683}]},
                 {wings,init_part2,3,[{file,"wings.erl"},{line,108}]},
                 {proc_lib,init_p_do_apply,3,
                           [{file,"proc_lib.erl"},{line,249}]}]}}