According to the SMCR model, problems in communication can arise when the speaker fails to do what?
Have a clue would be first on the list. If the source/sender doesn't fully understand his own intended message, he has very little chance of conveying said message through encoding/channel. Encoding then becomes an issue if the source/sender has mis-read his receiver and begins to encode said message in a manner unfamiliar to the receiver. There must be some reasonable expectation of decoding for proper encoding to be successful. Once in channel, the sender begins to look for signs of reception, decoding and feedback, while the receiver is then preparing to become the sender.