Problems with running Wald Test in Julia - statistics

Question

i´ve a problem with running the following function to perform a Wald Test on my Data. It always displays me the error message that the variable theta is not defined. I tried to define it in struct WaldTestFun{F, T, Z} but this does not work. The error message im getting is
Error Message = UndefVarError: theta not defined
Here is a part of the code:
using LinearAlgebra
using Optim
using PrettyTables
using Printf
using Statistics
using StatsBase
using StatsFuns
struct WaldTest
tbl::NamedTuple
rankmin::Int64
rankₘₐₓ::Int64
end
struct WaldTestFun{F, T, Z}
f::F
r::Int64
vecsigma::T
Vhat::Z
end
(wf::WaldTestFun)(theta) = wf.f(theta, wf.r, wf.vecsigma, wf.Vhat) #Here the error occurs
function waldobjfun(th, r, vecsigma, Vhat)
r,k = size(theta) #Here the error occurs
theta = reshape(theta, r+1, length(th)÷(r+1))
sigmamat = diagm(0=>theta[1,:].^2) .+ theta[2:r+1,:]'*theta[2:r+1,:]
tempsigma = sigmamat[findall(tril(ones(size(sigmamat))).==1)]
(vecsigma -tempsigma)' /Vhat *(vecsigma - tempsigma)
end
X = randn(100,10);
fm = Factotum.FactorModel(X, 3)
function waldtest(fm::FactorModel, minrank::Int = 0, maxrank::Int = 2)
X = copy(fm.X)
T, n = size(X)
## Normalize factor
Xs = X / diagm(0=>sqrt.(diag(cov(X))))
covX = cov(Xs)
meanX = mean(Xs, dims=1)
vecsigma = vech(covX)
bigN = length(vecsigma)
Vhat = Array{Float64}(undef, bigN, bigN)
varvecsig = zeros(n,n,n,n);