Question: How can I resolve the problem of asking "Error, (in Engine:-Dispatch) badly formed input to solve: not fully algebraic"?

Dear All,

I am facing some problems. This kind of error has been shown "Error, (in Engine:-Dispatch) badly formed input to solve: not fully algebraic"

eqn1 := {((1+1/beta).(diff(f(eta), eta, eta, eta))-(1+F[s]).((diff(f(eta), eta))^2)+(diff(f(eta), eta, eta)).f(eta)+M.(A-(diff(f(eta), eta)))-1/(R.D[a]).(diff(f(eta), eta)) = 0, diff(theta(eta), eta, eta)+4/3.N.(diff((1+(K-1).theta(eta))^3.(diff(theta(eta), eta)), eta)))+Pr.f(eta).(diff(theta(eta), eta))+(1+1/beta).Pr.Ec.((diff(f(eta), eta, eta))^2)+M.Ec.((diff(f(eta), eta)-A)^2) = 0, f(0) = 0, theta(0) = 1+alpha.(D(theta))(0), theta(10) = 0, (D(f))(0) = 1+(1+1/beta).lambda.(D(D(f)))(0), (D(f))(10) = 0};
;
sys1 := eval(eqn1, {A = 1, Ec = .2, K = 2.5, M = .5, N = .5, Pr = 6.5, R = 1, alpha = .5, beta = 2, lambda = .5, D[a] = .3, F[s] = 1});
sol1 := dsolve(sys1, numeric);
Error, (in Engine:-Dispatch) badly formed input to solve: not fully algebraic
with(plots);
t1 := odeplot(sol1, [eta, diff(f(eta), eta)], eta = 0 .. 10, numpoints = 65, thickness = 0, color = green, linestyle = solid);
plots[plots:-display]({t1})

MAXR.mw