??? Subscript indices must either be real positive integers or logicals.

Hey guys,
My program was working fine, until today when I run it and it displays this error:
??? Subscript indices must either be real positive integers or logicals.

What does it mean? And please suggest what I can do to my program? My project grading is tomorrow! Pls help!

Program:
darkCarValue = 60;
darkCar = rgb2gray(read(trafficObj, 1));
maskDarkCar = darkCar;
noDarkCar = imextendedmax(maskDarkCar,darkCarValue);
figure, imshow(darkCar)
figure, imshow(noDarkCar)
sedisk = strel('disk',1);
noSmallStructures = imopen(noDarkCar, sedisk);
figure, imshow(noSmallStructures)

nframes = get(trafficObj, 'NumberOfFrames');
I = read(trafficObj, 1);
taggedCars = zeros([size(I,1) size(I,2) 3 nframes], class(I));
 
for k = 1 : nframes
singleFrame = read(trafficObj, k);
I = rgb2gray(singleFrame);
        noDarkCars = imextendedmax(I, darkCarValue);
noSmallStructures = imopen(noDarkCars, sedisk);
noSmallStructures = bwareaopen(noSmallStructures, 150);
L = bwlabel(noSmallStructures);
taggedCars(:,:,:,k) = singleFrame;

if any(L(:))
stats = regionprops(L, {'centroid','area'});
areaArray = [stats.Area];
[junk,idx] = max(areaArray);
c = stats(idx).Centroid;
c = floor(fliplr(c));
width = 2;
row = c(1)-width:c(1)+width;
col = c(2)-width:c(2)+width;
taggedCars(row,col,1,k) = 255;
taggedCars(row,col,2,k) = 0;
taggedCars(row,col,3,k) = 0;
end
end