S-function _Error in port widths or dimensions

hello everyone, i use S-Function block (with m file) in a simulink model. 71 measuring signals are passes to the input port of S-Function block through a Mux. the output port of block are connected to demux to pass 45 signals. the following error are returned:

`Invalid setting for output port dimensions of 'DN_77bus77bus/Mux'. The dimensions are being set to 71. This is not valid because the total number of input and output elements are not the same

Error in port widths or dimensions. Input port 1 of 'DN_77bus77bus/S-Function' is a one dimensional vector with 71 elements`.

please how i can solve this problem.