ffmpeg BATCH conversion script in DOS command
 

I have problems with BATCH function in ffmpeg; here is what I use for single file and it works OK

VIDEO OK
ffmpeg -i c:\a\videos\358_5308_01.mxf -vcodec copy -acodec copy -y c:\a\converted\358_5308_01conv.m2t
AUDIO OK
ffmpeg -i c:\a\videos\358_5308_01.mxf -map 0:0 -vcodec copy -map 0:1 -acodec copy -y c:\a\converted\358_5308_01conv.wav

but for BATCH conversion I found this script online (all mxf files and ffmpeg are in c:\ location) but the script shows "%%a was unexpected at this time" error message.

for %%a in ("*.mxf") do ffmpeg.exe -i "%%a" -vcodec copy -acodec copy -y "%%~na_conv.m2t"

there must be some easy trick to make this BATCH thing work in DOS. Please help.