Parser requires integer length for vector after supplying integer length

I want to declare a one-dimension vector of length N called fd at the top of model block.
Error message was “PARSER EXPECTED: vector length declaration: integer expression in square brackets”, which was not reproduced in the code simulation here.
I have confirmed that N is an integer declared in the data block(first line). I did not see conflict in variable names. N has been used as vector length in previous declarations without any problem.

    int<lower=0> N;               // number of observation
    int<lower=0> S;               // number of studies
    int<lower=0> Gmax;            // largest number of dose groups
    int<lower=0,upper=Gmax> G[S]; // number of dose groups

    vector[N] ymeanL;             // ymean log
    vector[N] ysdL;               // ysd log
    vector<lower=0>[N] Nsub;      // number of subjects
    row_vector[N] dose;           // dose
  transformed data{
    row_vector[N] dosed;          // transformed dose
    dosed = ( dose - min(dose) ) / ( max(dose) - min(dose) );
    real<lower=0> sigma;
    real<lower=0> c;
    real<lower=1,upper=15> g;
    vector<lower=0>[S] a;
    vector<lower=0>[S] b;
    real mu_a;
    real<lower=0> sigma_a;
    real mu_b;
    real<lower=0> sigma_b;
    vector<lower=0>[N] fd;              
    int pos;              

    // Priors
    sigma ~ uniform(0,10);
    mu_a ~ uniform(-2,2);
    sigma_a ~ uniform(0,2);
    mu_b ~ uniform(-3,3);
    sigma_b ~ uniform(0,2);
    c ~ uniform(0,15);
    g ~ uniform(1,15);
    // Parameters
    a ~ lognormal(mu_a,sigma_a);
    b ~ lognormal(mu_b,sigma_b);
    // Hill equation
    pos = 1;                          
    for(s in 1:S){
      for(gg in pos:(pos+G[s]-1)){
        fd[gg] = a[s] + ( b[s] * dosed[gg]^g ) / ( c^g + dosed[gg]^g );
      pos = pos + G[s];

    // Likelihood
    target += -( Nsub/2*log(sigma^2) +  ( Nsub*(ymeanL-log(fd))^2 + (Nsub-1)*ysdL^2 ) /
    (2*sigma^2) );

I believe this is because you’ve declared the vector with a constraint:

vector<lower=0>[N] fd; 

Constraints aren’t used in the model block


Andrew thank you so much!
After removing the constraint, this declaration was recognized. Your suggestion totally solved my problem.

Since constraints aren’t used in the model block, I will look for other ways to set constraints for this variable. Thank you again!