sorry! My fault - shame on me!
dcraw.exe was in %PATH% but i had the file from the wrong binary release of ImageMagick (out of a 64bit "ImageMagick-7.0.3-1-Q16-x64-dll.exe" installation instead of 32bit). Now i have the draw.exe out from the portable binary "ImageMagick-7.0.3-1-portable-Q16-x86.zip" and everything works fine.
Thanks for pointing me to the right direction!
dcraw.exe was in %PATH% but i had the file from the wrong binary release of ImageMagick (out of a 64bit "ImageMagick-7.0.3-1-Q16-x64-dll.exe" installation instead of 32bit). Now i have the draw.exe out from the portable binary "ImageMagick-7.0.3-1-portable-Q16-x86.zip" and everything works fine.
Thanks for pointing me to the right direction!