following the instructions in the alpha-README.md file on GitHub
got an error on the claim-on-sidechain part
anyone dealt with it before?

    ./elements/contrib/sidechain-manipulation.py claim-on-sidechain 2N8qM71fbG1DiWcuDCLP7negcKq3X1rmhyE 2452357eb5e1e471378ebda207e4305b d93beb30b86971b79b9cac9e42d5bd0ed3ad66354e9d6c006ee39fb2ae1d52b9

Redeeming from utxo 4a466058a8754698a95ff29bc8bece97e1e131dfda29f76d30c958903fd85eb0:1 (value 20994180.93597788, refund 20994180.68597788)
sh: 1: /home2/CRYPTO/elements/contrib/../../alpha-tx: not found
Traceback (most recent call last):
  File "./elements/contrib/sidechain-manipulation.py", line 235, in <module>
    assert(cht.close() == None)
AssertionError