Solver Issue

How do I utilize the solver function in VBA without referencing cells but instead using my variables in VBA? Here t is not changing. I get no errors but it's not solving for t,it remains 1 at the end.

t = 1
SolverReset
SolverOk SetCell:="(2 * Application.Abs(msol) * 3 * Radius) / ((Pi / 4) * (Radius ^ 4 - (Radius - t) ^ 4))", MaxMinVal:=3, ValueOf:=AllowStress, ByChange:="t"
SolverSolve userFinish:=True
SolverFinish KeepFinal:=1

Worksheets("ReadMe").Range("A2") = t

Thanks,