How to change the signal dimension on each loop?

Hey, I receive the following error message when trying to run the Simulink model:

Unable to determine signal dimensions. There is a loop consisting of '/Delay2' that cannot be resolved because signal dimensions are defined by a cyclic relationship. Specifying the signal dimensions on Inport, Mux, Selector, Demuxes will help resolve signal dimensions in the loop. You can also use the Signal Specifications to define the signal dimensions.

The inport of the matlab function must contain all previously calculated vectors.

Thank you for any suggestions!