# a problem of substitution with a rule

I would to make this substitution with 2 rules. Nothing is happening.

     (Sin[η2] ((Cos[θ2]* Cos[ψ1])/Sin[ψ1] +
Cos[ψ2] Sin[θ2]) == Cos[η2] Sin[ψ2]) /.
Sin[ψ1] -> (Cos[ϕ2] Sin[η2])/Sin[ψ2] /.
Cos[ψ1] -> Cos[η2] Cos[θ2] Cos[ϕ2] -
Sin[θ2] Sin[ϕ2]


Have you an idea why i didn't manage to make these substitutions ? Sorry if my question is may be very simple, but i blocked.

Use HoldForm to stop Mathematica from simplifying,
SC = HoldForm[(Sin[\[Eta]2] ((Cos[\[Theta]2]*Cos[\[Psi]1])/