Hello,

what is wrong?

HRest -A -D -T 1 -C de.hcompv.config -M hmm1 -I hmm0/hmmdefs -H hmm0/vFloors

HTK Configuration Parameters[10]
  Module/Tool     Parameter                  Value
#                 NUMCEPS                       12
#                 CEPLIFTER                     22
#                 NUMCHANS                      26
#                 PREEMCOEF               0.970000
#                 USEHAMMING                  TRUE
#                 WINDOWSIZE         250000.000000
#                 SAVEWITHCRC                 TRUE
#                 SAVECOMPRESSED              TRUE
#                 TARGETRATE         100000.000000
#                 TARGETKIND          MFCC_0_D_N_Z

  ERROR [+6551]  LoadMasterFile: MLF file header is missing
 FATAL ERROR - Terminating program HRest

I'm not sure where did you take this command from. Your command is wrong. -I should specify mlf file, not hmm defs. For hmmdefs you need -H. The correct command should be something like:

HRest -A -D -T 1 -C de.hcompv.config -M hmm1 -H hmm0/hmmdefs -H hmm0/vFloors -I phones.mlf hmmlist

I suggest you to use proper tutorial like the one from here http://www.voxforge.org/home/dev/acousticmodels/linux/create/htkjulius/tutorial or htkbook, it's not trivial to guess all arguments properly.