In your Gravity function you have some variable name inconsistencies. E.g.,
function dRV = Gravity(t, RV)
global T X_J Y_J Z_J X_M Y_M Z_M X_E Y_E Z_E mu_E mu_M mu_J mu_S
X = R(1);
Y = R(2);
Z = R(3);
VX = R(4);
VY = R(5);
VZ = R(6);
:
dR(1) = VX
dR(2) = VY
dR(3) = VZ
dR(4) = dV * X
dR(5) = dV * Y
dR(6) = dV * Z
So, you pass in a variable named RV, but then access it using the variable name R. And your output variable is named dRV in the function line, but you use the name dR in your code. You need to pick consistent variable naming for these.
