Substituting values for syms yet answer still in terms of syms

I am trying to substitute an initial value (t=0) for "t" in my code but my results are still in terms of "t" and not zero. I commented the problematic output in the code below.

%%Variables

syms phi1 phi2 phi3 x1 y1 x2 y2 x3 y3 t
%%Geometry of Slider-Crank
L1 = 1.4;
L2 = 1.8;
e = 0.15;
r1 = [x1;y1];
r2 = [x2;y2];
r3 = [x3;y3];

%%Roatation Matrices
A1 = [cos(phi1) -sin(phi1);sin(phi1) cos(phi1)];
A2 = [cos(phi2) -sin(phi2);sin(phi2) cos(phi2)];
A3 = [cos(phi3) -sin(phi3);sin(phi3) cos(phi3)];
B1 = [-sin(phi1) -cos(phi1);cos(phi1) -sin(phi1)];
B2 = [-sin(phi2) -cos(phi2);cos(phi2) -sin(phi2)];
B3 = [-sin(phi3) -cos(phi3);cos(phi3) -sin(phi3)];
R = [0 -1;1 0];

%%Relative Coordinates
s1O = [-L1/2; 0];
s1P = [L1/2; 0];
s2P = [-L2/2;0];
s2Q = [L2/2;0];
s3Q = [0;0];
v3X = [1;0];
rO  = [0;0];
rR  = [0; -e];
vY  = [0;1];

%%Jacobian

   q = [r1.',phi1,r2.',phi2,r3.',phi3];
  PHI(q) =[r1+A1*s1O; r1+A1*s1P-r2-A2*s2P; r2+A2*s2Q-r3; (vY.')*(r3-rR); (vY')*A3*v3X; phi1-pi/3-0.5*t-t^2];
  % 
   Jq = jacobian(PHI,q);
  Jt =jacobian(PHI,t);

%%Newton Raphson Method: Determining Initial Position

q0= [0.34; 0.61; pi/3; 1.26; 0.53; -pi/3; 2; -0.16; 0.01];

t=0;
dq0= [0;0;0;0;0;0;0;0;0];

for i=1:1:5
    q0=q0+dq0;

x1 =q0(1,1);
y1 =q0(2,1);
phi1=q0(3,1);
x2=q0(4,1);
y2=q0(5,1);
phi2=q0(6,1);
x3=q0(7,1);
y3=q0(8,1);
phi3=q0(9,1);

r1 = [x1;y1];
r2 = [x2;y2];
r3 = [x3;y3];
q = [r1.',phi1,r2.',phi2,r3.',phi3];

A1 = [cos(phi1) -sin(phi1);sin(phi1) cos(phi1)];
A2 = [cos(phi2) -sin(phi2);sin(phi2) cos(phi2)];
A3 = [cos(phi3) -sin(phi3);sin(phi3) cos(phi3)];
B1 = [-sin(phi1) -cos(phi1);cos(phi1) -sin(phi1)];
B2 = [-sin(phi2) -cos(phi2);cos(phi2) -sin(phi2)];
B3 = [-sin(phi3) -cos(phi3);cos(phi3) -sin(phi3)];
R = [0 -1;1 0];

PHI0 =[r1+A1*s1O; r1+A1*s1P-r2-A2*s2P; r2+A2*s2Q-r3; (vY.')*(r3-rR); (vY')*A3*v3X; phi1-pi/3-0.5*t-t^2];
Jq0=Jq(x1,y1,phi1,x2,y2,phi2,x3,y3,phi3);
d=Jq0\-PHI0;
dq0=double(d);
end
position = q0

%%Velocity Equation Solving for the vector of generalized velocities(q dot)
t0=0;
Jt0=subs(Jt,t,0);  %%PROBLEM still outputs in terms of t
vpa(Jt0,10)

Any suggestions are appreciated

Thank you,

Joey