Dear Kirt,

Thanks for your answer. I made several mistakes in my first post here, sorry for that, this is my fault. I corrected them since when.
I am using 15 directions, 2 non-zero b-values.
I did not include the b0 to my table, and I have 15 lines, 3 columns in it.

When I look at the created Nifti files, the images for 15 directions and each b-value are there, in the 'combined' folder. But they are the last images that are created before the error occurs.
I attached my data in the native structure, with the DKEParameters.dat and bvecs.txt files in there.

Clementine