I am using argument encoding from this page (https://github.com/ethereum/wiki/wiki/Ethereum-Contract-ABI) to build data field for offline signing. I am using eth.sendRawTransaction to call a function in my deployed smart contract. Everything is working fine when the functions have arguments (1 or more), but I am getting an "invalid opcode" exception for the functions which have no arguments. I am using just the first four bytes of the function selector (i.e, sha3('myFunc()')) since there are no arguments.
These functions are working fine when I use a dummy argument (keeping the rest same).
Is there a special way to handle functions without arguments ?