Dear Carlo Corti,
Thank you for your detailed explanation.
IUCLID 5.3 is not yet supported by the QSAR Toolbox and that's why you get the error message. Support for IUCLID 5.3 will be added in version 3.0 of the Toolbox. By then, there are several options which you can try to transfer your IUCLID data into the Toolbox
1) Export to i5z's and then use the Toolbox batch import (which will be available as of version 2.2 of the Toolbox)
2) Transfer your IUCLID data to a IUCLID 5.2 server and then use the Toolbox WebServices wizard (as you did)
3) (hypothesis, untested) You may try running IUCLID 5.3 but with an older version of the WebServices module (if you have one from a previous setup).
I'll be following the topic in case you have further questions.
Many thanks for your prompt answer. I think that it's safest to wait for the new QSAR Toolbox releases instead that to play with WebServices in a production environment.
I hope that at least the 2.2 Toolbox version will be available in a reasonable time