Probleming using gnu sed in windows batch script

I want to use gnu sed for windows (available here: http://gnuwin32.sourceforge.net/packages/sed.htm)
to replace some bytes in file test.txt by other bytes.


Therefore I created (on 64bit Windows 7) the following DOS batch script:


echo start
sed 's/\xc3\xbc/\xtc/g' <test.txt >testnew.txt
pause




However when I run this batch script by double clicking I got the following error:


sed: -e expression #1, char 1: unknown command: `''


Why?


Thank you
Ben