Why do I receive an illegal rate transition error when I believe I am using the correct rules for the transition?

Why do I receive an illegal rate transition error when I believe I am using the correct rules for the transition?

When I follow the rate transition rules in my model with D Flip Flops, I get the following error message

 Illegal rate transition found involving Unit Delay block 'delta_sigma/Five Stage D Flip Flop/Unit Delay6'. When using this block to transition rates, the input must be connected to the slow sample time and the output must be connected to the fast sample time. The Unit Delay must have a sample time equal to the slow sample time and the slow sample time must be a multiple of the fast sample time

Answer 1

[MathWorks Support Team]

This problem has been fixed in Simulink 4.1 (R12.1).

If you are using Simulink 4.0 and this error is being caused by the last unit delay block inside of a Subsystem, you may want to try moving the Unit Delay outside of the Subsystem.

Please change the mode to Single-tasking when running your model, as this should eliminate the errors.