multisig refund broadcast to bitcoin network fails

[funcho]

 

i think i send btc from bitstamp to a multisig account
and now we agreed to send me btc back

they signed the transaction and gave me a hex

i signed it too and when i want to broadcast i get error message

i use a recieving address from electrum with their private key

 16: mandatory-script-verify-flag-failed (Operation not valid with the current stack size)
i use coinb.in

so i guess i need the privat key from the address i have send the transaction
NO OTHER WAY ?   does bitstamp provide this ?

[superresistant]

 
I hope this thread might help :

"Operation not valid with the current stack size" when spending from 2of3
https://bitcointalk.org/index.php?topic=1823847.0