Compilation error

Questions
1

Can anyone help me understand why the Compile fails here:

f = Compile[{{\[Sigma]t, _Real, 1}, {s\[Rho], _Complex, 
    1}, {dt, _Real, 1}, {x, _Real}, {nnt, _Integer}},
  
  Module[{kz = 1/2 x, \[Sigma] = \[Sigma]t, d = dt, i, kp, c, \[Beta],
     r, k, \[Rho] = s\[Rho] * 10^-6, nn = nnt},
   kp = kz + 0. I;
   k = Sqrt[kz^2 - 4 \[Pi] (\[Rho][[2]] - \[Rho][[1]])];
    r = (kp - k)/(kp + k) E^(-2 kp k \[Sigma][[1]]^2);
   c = {{1 + 0. I, r }, {r , 1 + 0.}};
   kp = k;
   
   For[i = 2, i < 2 nn + 2, i++,
    
    If[EvenQ[i],
     k = Sqrt[kz^2 - 4 \[Pi] (\[Rho][[3]] - \[Rho][[1]])];
     
      r = (kp - k)/(kp + k) E^(-2 kp k \[Sigma][[2]]^2); \[Beta] = 
      I kp d[[1]],
     
     
     k = Sqrt[kz^2 - 4 \[Pi] (\[Rho][[2]] - \[Rho][[1]])];
     
      r = (kp - k)/(kp + k) E^(-2 kp k \[Sigma][[3]]^2); \[Beta] = 
      I kp d[[2]] 
     
     
     ];
    
    
    c = c.{{E^\[Beta], r E^\[Beta]}, {r E^-\[Beta], E^-\[Beta]}};
    
    (*previous k*)
    kp = k
    ];
   
   Abs[(c[[2, 1]] + 1*^-100 + I 1*^-200 )/(
    c[[1, 1]] + 1*^-100 + I 1*^-200)]^2]
  
  
  
  , CompilationTarget -> "C"]

In[43]:= f[{0, 0, 0}, {0, 24, 5}, {6, 4}, 0.025, 1000]

During evaluation of In[43]:= CompiledFunction::cfne: Numerical error encountered; proceeding with uncompiled evaluation. >>

Out[43]= 1.00000000000000