Error while calling contract entry point on Carthagenet

When I send this parameter in a call to a smart contract entry point on Carthagenet, it fails. Nevertheless, on Babylonnet it used to work:

{“entrypoint”:”default”,”value”:{“args”:[{“args”:[{“args”:[{“args”:[{“args”:[{“int”:”3000000″},{“string”:”11111111″}],”prim”:”Pair”},{“string”:”Stuart”}],”prim”:”Pair”},{“int”:”33333333″}],”prim”:”Pair”}],”prim”:”Left”}],”prim”:”Left”}}

The JSON is valid (checked with a JSON prettifier tool) and it is just like the one generated by SmartPy’s explorer. Just one difference is the order of the JSON elements (i.e.: instead of {“prim”:”Left”, “args”:[]}, I have: {“args”:[], “prim”:”Left”})