Julia Error

function ShortestPath(DAG, K2Score)

for i = 1:length(K2Score)
  ind = findall(K2Score .== 0.0)
   #K2Score[1,ind] ~= root,
      K2Score[1,ind] = 0.01

end


#  Finding the root.
G = DAG
M,N = size(DAG)
k = 1
for i in 1:M
    for j in 1:N
        if G[i,j] ~= 0
            a[1,k] = i
            a[2,k] = j
            k = k +1
        end
    end
end


##
n = k-1
k = 1;
for j in 1:N
    flag = 0
    for i in 1:M
        if G[i,j] ~= 0
            flag = 1
        end
    end
    if flag .== 0
        root[1,k] = j; # Must store all the values
        k = k+1
    end
end

## Applying bellman algorithm


for ii = 1:length(root)

k =1
for i = 1:n
    if a[1,i] .== root[1,ii]
        b[1,k] = a[1,i]
        b[2,k] = a[2,i]
        k = k+1
    end
end


for i = 1:n
    if a[1,i] ~= root[1,ii]
        b[1,k] = a[1,i]
        b[2,k] = a[2,i]
        k = k+1
    end
end



for i = 1:M
    for ii = 1:length(root)
    dist[ii,i] = 20000; # infinity Value
    end
end

dist[ii,root[1,ii]] = 0
 for i = 1: M
     for j = 1:n
         k = dist[ii,b[1,j]] + 1
         if k .< dist[ii,b[2,j]]
             dist[ii,b[2,j]] = k
         end
     end
 end
## Finding the minimum of distance
final_dist = minimum(dist, dims = 1)

end

return final_dist

end