Superposition of two plots: (1) plot matrix (2) horizontal lines.

Hello, I want to plot points from a 26x2 matrix and two horizontal lines representing an interval around the maximum value, all three in the same figure. I manage to plot the matrix point by using plot matrix but I can't plot the two horizontal lines (I tested these horizontal plots separately and they worked). I only see two short dashes on the y-axis. This is my code :

 %
E_matrix = [0 97594105.7877297;1 91689045.4803060;2 94667284.1402778;...
    3 98150602.9496285;4 97601187.4310221;5 97297406.4860670;...
    6 96119910.2269929;7 94235325.5743332;8 91103945.5378485;...
    9 86252148.8764753;10 83117717.2198853;11 79810687.5818826;...
    12 73705295.6152776;13 69472079.8383885;14 63535971.8214140;...
    15 57263601.5065311;16 51282327.8999928;17 47099704.4723444;...
    18 43603813.7767508;19 40128819.9041277;20 36938571.2842874;...
    21 33499378.1981204;22 31561049.5334555;23 29460985.2107030;...
    24 25814629.3522583;25 22907368.6361586];
f=1;
while E_matrix(f,2)>E_matrix(f+1,2)
    E_matrix(f,:)=[];
    f=f+1
end   
figure(1);
plotmatrix(E_matrix(:,1), E_matrix(:,2));
Int_prec=0.05;
Emax=max(E_matrix(:,2));
max_E_Int=Emax+Int_prec*Emax;
min_E_Int=Emax-Int_prec*Emax;
x_line=[0 26];
y_line_min=[min_E_Int min_E_Int];
y_line_max=[max_E_Int max_E_Int];
hold on;
line(x_line, y_line_min,'Color','red')
hold on;
line(x_line,y_line_max,'Color','red')
plotmatrix(E_matrix(:,1), E_matrix(:,2))

Could you help me please?