0 values from tcksample


I am using the tcksample function to obtain FA, RD, MD and AD measurements for my tractography. In some of my participants, the values in the csv files for all measurements are 0 (attached image). I have checked the tractography and it is the same as all the other participants. The script I have used for all the participants are:

tcksample label_7.tck FA.mif label_7_FA.csv
tcksample label_7.tck MD.mif label_7_MD.csv
tcksample label_7.tck RD.mif label_7_RD.csv
tcksample label_7.tck AD.mif label7_AD.csv

Is there any idea what could be wrong here?