请教各位大神，用NSolve解出的解反代回方程，结果与求解的不相等。比如说NSolve[dd==0,cc]，解出的结果cc代入式子dd，结果dd≠0。
为什么出现这种情况，怎么办

w = 794; u0 = 10^5; c1 = u0; c2 = u0/2; c4 = u0/2; c3 =
10^9; r = 1.0001; c5 = u0*(r + 1)^2/8/r; d1 = u0*(r - 1)^2/r; d2 =
u0*(1 - r^2)/r; p = 10^3; t1 = 10^(-2); t2 = 0.5*10^(-4); tr =
10^(-6); c11 = (1 - I*w*tr)*(2*c1/9 - 4*c2/3 + 2*c3 +
20*c4/9); c13 = (1 - I*w*tr)*(-4*c1/9 + 2*c2/3 + 2*c3 -
4*c4/9); c33 = (1 - I*w*tr)*(8*c1/9 + 8*c2/3 + 2*c3 +
8*c4/9); c44r = (1 - I*w*tr)*(2*c5 -
d2^2*(1 - I*w*t2)^2/(4*d1*(1 - I*w*t1)*(1 - I*w*tr))); B =
16*10^9;(*杨氏模量*)v = 0.35; G = B/(2*(1 + v));(*剪切模量*)lamda =
2*v*G/(1 -
2*v);(*拉梅常数*)p0 = 2680; vp = 3095; vs = 1487; bb1 = \[Sqrt](-1/(
2*c33 c44r) (c13^2 - c11 c33 + 2 c13 c44r + cc c33 p +
cc c44r p + \[Sqrt](-4 c33 c44r (c11 - cc p) (c44r -
cc p) + (c13^2 - c11 c33 + 2 c13 c44r +
cc (c33 + c44r) p)^2))); bb2 = \[Sqrt](-1/(
2*c33 c44r) (c13^2 - c11 c33 + 2 c13 c44r + cc c33 p +
cc c44r p - \[Sqrt](-4 c33 c44r (c11 - cc p) (c44r -
cc p) + (c13^2 - c11 c33 + 2 c13 c44r +
cc (c33 + c44r) p)^2))); rr2 =
Sqrt[(lamda - cc*p0 + 2*G)/(lamda + 2*G)]; rr1 =
Sqrt[(G - cc*p0)/
G]; fai1 = (p*cc - c11 + c44r*bb1^2)/(I*
bb1*(c13 + c44r)); fai2 = (p*cc - c11 + c44r*bb2^2)/(I*
bb2*(c13 + c44r)); pusai1 = -(rr1^2*G - (lamda - cc*p0 + 2*G))/(I*
rr1*(lamda + G)); pusai2 = -(rr2^2*G - (lamda - cc*p0 + 2*G))/(I*
rr2*(lamda + G)); D11 = 1; D12 = 1; D13 = -1; D14 = -1; D21 =
I*fai1; D22 = I*fai2; D23 = -I*pusai1; D24 = -I*pusai2; D31 =
I*(-I*c13 + fai1*bb1*c33); D32 = I*(-I*c13 + fai2*bb2*c33); D33 =
I*(pusai1*rr1*(2*G + lamda) + I*lamda); D34 =
I*(pusai2*rr2*(2*G + lamda) + I*lamda); D41 = -c44r*(I*fai1 -
bb1); D42 = -c44r*(I*fai2 - bb2); D43 = G*(rr1 + I*pusai1); D44 =
G*(rr2 + I*pusai2); d = {{D11, D12, D13, D14}, {D21, D22, D23,
D24}, {D31, D32, D33, D34}, {D41, D42, D43, D44}}; ddd =
Simplify[d]; MatrixForm[ddd]; dd = Det[ddd]; NSolve[dd == 0, cc]