Bootstrap in Matlab 2013 compute covariance matrix and mean

Question

Below is the code and the error message. I am trying to compute bootstraped covariance matrix and mean. Any idea why I am getting not consistent dimensions?

Regards,

RawReturn = csvread('Raw return data.csv');
bootstat = bootstrp(1000, @(x)[mean(x), cov(x)], RawReturn);
-------------------------------------------------------------

Error using horzcat
Dimensions of matrices being concatenated are
not consistent.

Error in @(x)[mean(x),cov(x)]


Error in bootstrp (line 167)
 bootstat = feval(bootfun,bootargs{:});

Error in Efficient_frontier (line 2)
bootstat = bootstrp(1000, @(x)[mean(x), cov(x)],
RawReturn);

Caused by:
Unable to evaluate BOOTFUN with the supplied
arguments.