Our forum software changes how hyphens appear, so it can be difficult to tell exactly what you wrote. I think you have two hyphens before g and b, but these should only have one. Try running this:
"C:\Program Files\BrainSuite21a\bdp\bdp.exe" 2523412.bfc.nii.gz --tensor –-nii 2523412.dwi.nii.gz -g 2523412.dwi.bvec -b 2523412.dwi.bval
and see if that fixes the problem.