exponential fit

hi,i would like to fit data using a loop for every 5 points(values) which would shift(move) to one next value.

clc
format long
load C:\matlab_prog\IRC_2011_11_18_15_23_26_TEST04_charg.dat
A=IRC_2011_11_18_15_23_26_TEST04_charg
A(:,1)=[]
Z=length(A)
Y=A(1,2)
B=zeros(Z,2);
B(:,2)=[Y;]
C=A-B
B=C
D=C
B(:,1)=[]
D(:,2)=[]
loglog (B,D,'*')
hold on 
X=3
O=7
%X2=4
%P=zeros(Z-X,5)
while O<Z
    E=C(X:O,:)
    M=E(1,2)
    N=E(5,2)
    G=E
    H=E
    G(:,1)=[]
    H(:,2)=[]
    H1=rot90(H)
        if H1(1)~=H1(3) 
        X=X+1
        O=O+1    
        loglog(G,H,'x')
        hold on
        s=exp2fit(G,H,1)
        fun = @(s,G) s(1)+s(2)*exp(-G/s(3));
        tt=linspace(M,N,5); 
        ff=fun(s,tt); 
        loglog(tt,ff,'red');
        hold on
        %end
        else %H1(1)==H1(5)
        X=X+1
        O=O+1    
        end
    %S1=ones(1,5)
    %S1=S1*s(1)
    %S2=ones(1,5)
    %S2=S2*s(2)
    %S3=ones(1,5)
    %S3=S3*s(3)
    %R=[tt;ff;S1;S2;S3]
    %R=rot90(R)
    %if X==3
        %P=R(1:3,:)
    %else X<Z
        %P(X2,:)=R(3,:)
        %X2=X2+1

end

??? Error using ==> snls at 269 lsqcurvefit cannot continue: user function is returning Inf or NaN values.

Error in ==> lsqncommon at 231 [x,FVAL,LAMBDA,JACOB,EXITFLAG,OUTPUT,msg]=...

Error in ==> lsqcurvefit at 186 [x,Resnorm,FVAL,EXITFLAG,OUTPUT,LAMBDA,JACOB] = ...

Error in ==> exp2fit at 205 [s,RESNORM,RESIDUAL,EXIT]=lsqcurvefit(fun,s0,t,f,[],[],options);

Error in ==> fit2 at 35 s=exp2fit(G,H,1)