Hi Thomas,
First of all, thank you for your answer. I am a little bit stressed because I have tried a lot of things but noone seems to work properly.... And we should to send the KNIME workflows on Wednesday!
I compared the output of the first two nodes (2D MOE descriptor calculation and Z-normalization) with those obtained using MOE and a in-house programs directly. No differences were observed.
Then, I kept the training (TR) and test (TS) sets after their normalization (see workflow attached previously) in arff format to use them directly in WEKA. The TR.arff was correctly read and the same set of descriptors as obtained using WEKA directly was selected.
The problem came with the TS. After manually selecting the same set of descriptors as those selected for the TR, it was not possible to run any prediction. The only difference I noted when I checked the TR and TS, is that they do not present the same order in the descriptor list. For the TR, activity is placed in the last position while for the TS it is placed in the first position. Then, when I tried to run the model I got the mesage error "TS and TR set are not compatible".
Do you have any other idea? I would really appreciate it.
In any case, thank you in advance for your time and consideration.
With my best regards,
marta