Error: File: RTBPlot.m Line: 297 Column: 39

[SenudaJayalath]

This is the code I have entered,

Th_1 = str2double(handles.Theta_1.String)*pi/180;
Th_2 = str2double(handles.Theta_2.String)*pi/180;
Th_3 = str2double(handles.Theta_3.String)*pi/180;

L_1=20;
L_2=50;
L_3=40;

L(1) =Link([0 L_1 0 pi/2]);
L(2) =Link([0 0 L_2 0]);
L(3) =Link([0 0 L_3 0]);

Robot = SerialLink(L);
Robot.name = 'RRR_Robot';
Robot.plot([Th_1,Th_2,Th_3]);

When I run the Robot.plot this error comes up

Error: File: RTBPlot.m Line: 297 Column: 39
The input character is not valid in MATLAB statements or expressions.

Error in SerialLink/plot (line 213)
    opt = RTBPlot.plot_options(robot, varargin);

Given below is a picture of RTBPlot.m line 297. Could anyone please tell me how to resolve this problem