Unable to determine signal dimensions. There is a loop consisting of 'akash/Sum5' that cannot be resolved because sign...this is the message after running my simulink model

clear all;

close all;

clc;

kp=15.1*10^6;

rp=2210.7;

ms=6.2638;

ks=7.42*10^7;

kb=1.89*10^10;

mp=12.638;

g=9.81;

rs=1376.8;

mr=0.5;

rr=20;

kr=5;

n_mpg=-mp*g;

i_mp=1/mp;

these are the parameters of my simulink model;

[Sam Chak]

Unable to determine the error because cannot run the Simulink model.