'strcmp' function not working when called through another function, but works when used directly

 function Raw = pre_post(Data,ID,Sec)
lookup = {'Au Data Log ID','Measured CO','Measured Co2','Measured HC', 'Measured CH4', 'Measured NOx', 'Measured NO'};
Header = Data.Header(1,1:sum(~cellfun('isempty',Data.Header)));
lookup_location = zeros(1,length(lookup));
for i=1:length(lookup)
  lookup_location(1,i) = find(strcmp(Header,lookup{i}),1);
end

Rawdata = Data.Data(:,lookup_location);

zero = find(Rawdata(:,1)==ID(1));
Span = find(Rawdata(:,1)==ID(2));
Back = find(Rawdata(:,1)==ID(3));

Raw = mean(Rawdata(zero(1)+Sec(1):zero(1)+Sec(2),2));
end

I have the above code as a function, when i call the function as

Raw = pre_post(Data,ID,Sec);

I see an error

But code works if run without the function. Can someone tell me what is wrong with the function.

Answer 1

[KSSV]

Try this:

function Raw = pre_post(Data,ID,Sec)
lookup = {'Au Data Log ID','Measured CO','Measured Co2','Measured HC', 'Measured CH4', 'Measured NOx', 'Measured NO'};
Header = Data.Header(1,1:sum(~cellfun('isempty',Data.Header)));
lookup_location = cell(length(lookup),1);
for i=1:length(lookup)
  lookup_location{i} = find(strcmp(Header,lookup{i}),1);
end

Initialize lookup_location as a cell..cell can take non equal arrays. When you initialize lookup_location as a zeros matrix with 1 row..it expects only one element inside the loop using Strcmp..so the error popped out.