Answer
Does not make sense.
Work Step by Step
A cryptogram is a message written so that no one other than the intended recipient
can understand it.
The procedure (see p.637):
1. Assign each letter a numerical value, (A=1, B=2, ... Z=26, space=0)
2. Convert the numerical values of the message into a matrix.
3. Multiply with an inveritble matrix to code the message.
4. The recipient must know the inverse of the matrix (chosen in step 3) to decode the message.
So, there can be no error in coding (step 3), but, rather, when decoding (step 4).
If the recipient does not have the inverse of your matrix, the error will be made then.
If he does (have the inverse), all is well.
Does not make sense.
