Error requesting an attestation

I forked the experiment from this attestation https://www.beat-eu.org/platform/attestations/1839141191/ to https://www.beat-eu.org/platform/experiments/smarcel/aythamimm/btas15_keystroke_experiments/6/Keystroke_Experiment-rr2/ and failed to request an attestation to this one. I got a popup message "Error: Forbidden" !