lsqcurvefit - Dimensions of matrices being concatenated are not consistent

I am trying to do a nonlinear fit to a function using lsqcurvefit, and I get a "Dimensions of matrices being concatenated are not consistent" error. Below is the code I use, and the error I get. Any help will be appreciated.

>> t=[1 10 20 50 100 250];
>> v=10*t./(t+2);
>> test = @(a, x) a(1)*x./(x+a(2));
>> lsqcurvefit(@(a,t) test(a,t),[5 5],t,v)
Error using horzcat
Dimensions of matrices being concatenated are not consistent.

Error in color (line 9)
plotStr = [colors(1+mod(ind-1, length(colors))) plotOpt];

Error in snls (line 176)
   group = color(Jstr,p);

Error in lsqncommon (line 166)
            snls(funfcn,xC,lb,ub,flags.verbosity,options,defaultopt,initVals.F,initVals.J,caller, ...

Error in lsqcurvefit (line 257)
    lsqncommon(funfcn,xCurrent,lb,ub,options,defaultopt,caller,...

[Star Strider]

This runs for me without error:

t=[1 10 20 50 100 250];
v=10*t./(t+2);
test = @(a, x) a(1)*x./(x+a(2));
b = lsqcurvefit(test,[15 5],t,v);

On Windows 8.1, R2016a.