Plot function with different parameter

I have a problem with plot calculated function with various parameter. My code is:

N           = 22.5;
f           = 868;
d_ref       = 1;
floor_PLF   = [0, 9, 19, 24];
floor_n     = [0, 1, 2, 3];
dist_step   = 0.5;
dist_max    = 50; 
IPL         = zeros(4 ,300);
FSPL = 20 * log10(d_ref) + 20 * log10(f) - 28;
test = floor_PLF(3);
figure;
for counter = 1:length(floor_n)
    d = 0 : dist_step : dist_max;
    f_PLF = floor_PLF(counter);
    f_n = floor_n(counter);
    floorPL = f_PLF .* f_n;

      IPL = FSPL + N *log10(d/d_ref) + (floorPL(counter));   
      plot(d, IPL, '.'); hold on;

end

I get error: index exceeds matrix dimensions. in statement where I have IPL = FSPL .... And my code plot just one function, the first one.

I would like plot different function with different parameter from floor_PLF and floor_n array.

[Adam]

floorPL

appears to be scalar and there is no need to index into it with 'counter' since it is calculated within that loop each time.

IPL = FSPL + N *log10(d/d_ref) + (floorPL);

looks like it would work at a glance.