Problem with findpeaks function

Hey! I'm trying to find the natural frequency of a swinging pendullum in a few different states (with springs, without springs, with forcing, without forcing) and I need to find the natural frequency of the system from experimental data that I gathered from tests in a lab. I'm using the findpeaks function in matlab to get the peaks of data sets from 10 different trials, but I have a problem. The find peaks function is supposed to find local maxima, but my find peaks function continues to give me negative values interspersed with a few of the actual maxima of the data. I tried using the 'MinPeakHeight' feature to get rid of these values but I still kept getting negative values! Can someone help me? I would greatly appreciate any input anyone can give! My code is below.

clear;
close all
format short e

%% Call upon all data files

SpringNoForce = { '2S0.lvm';
                '2S1.lvm';
                '2S2.lvm';
                '2S3.lvm';
                '2S4.lvm';
                '2S5.lvm';
                '2S6.lvm';
                '2S7.lvm';
                '2S8.lvm';
                '2S9.lvm'};
            
SpringForce = { 'F2.0.lvm';
                'F3.5.lvm';
                'F3.6.lvm';
                'F3.7.lvm';
                'F3.8.lvm';
                'F3.9.lvm';
                'F4.0.lvm';
                'F4.1.lvm';
                'F4.2.lvm';
                'F4.3.lvm';
                'F4.4.lvm';
                '4.5.lvm';
                'F4.6.lvm';
                'F4.7.lvm';
                'F6.0.lvm'};
            
NoSpring = { '0S0.lvm';
             '0S1.lvm';
             '0S2.lvm';
             '0S3.lvm';
             '0S4.lvm';
             '0S5.lvm';
             '0S6.lvm';
             '0S7.lvm';
             '0S8.lvm';
             '0S9.lvm'};
         
%% Organize data
g = 9.81;
mc = 0.0503;
L = 0.4778375;
mw = 0.01;
mr = 0.0532;
lc = 0.33734375-(L/2);
lb = 0.3048;
Ir = (1/3)*mr*L^2;
xm = [.05,0.10,0.20,0.30];
Nm = [3.95,6.2,11.05,15.85];
kf = polyfit(xm,Nm,1);
k = kf(1);
sx = linspace(0,0.4,1000);
Ns = k.*sx+kf(2);

figure(1);
clf;
plot(sx,Ns)
hold on
plot(xm,Nm,'o')




for i = 1:length(NoSpring)
    figure
    hold on
    data1 = load(NoSpring{i});
    tns = data1(:,1);
    yns = data1(:,2);
    plot(tns,yns)
    [dpk,loc] = findpeaks(yns,tns,'MinPeakHeight',1);
    chloc = gradient(loc);
    wa(i) = mean(chloc);
    wde(i) = (2*pi)./wa(i);
    lw = (0.4429125+(0.001190625*(i-1))/2);
    Io(i) = Ir+mc*(lc-(L/2))^2+mw*(lw-(L/2))^2;
      for q = 2:(length(dpk)-1)
        delta(q-1) = (1/q)*log(dpk(q)/dpk(q+1));
    end
    ddel = mean(delta);
    ksee(i) = ddel/(sqrt(4*(pi)^2+ddel^2));
    wne1(i) = wde(i)/(sqrt(1-(ksee(i))^2));
    wnt(i) = sqrt((g*(mr*(L/2)+mc*(lc)+mw*(i-1)*lw))/Io(i));
    
     
end

[Juan Lasso Velasco]

Nevermind I found the problem. I left an extra loop at the end that was overwriting the values. I forget to include that in the code.