Cannot sign with ecdsa module in node js

I am trying to use the ecdsa module to sign some data with a crypto ecdh private key. My code is below:

shaMsg = crypto.createHash('sha256').update(myData).digest();
signed = ecdsa.sign(shaMsg, myECDHKey);

I am facing the following problem:

ERROR: Server - Caught exception: Error: Expected property "1" of type BigInteger, got Buffer

Can anyone help me?

via Dalton