"There must have at least two samples." would imply that your xnew does not have at least two rows in those cases.
For "one or more samples have no observations.": the second column of the input is expected to be the group number, which is expected to be a positive integer 1 through the number of groups. If there are any integers in the range 1 to floor(max(xnew(:,2)) which are not present in xnew(:,2) then you would receive this message.
The column 2 data that you are passing is the cdf you have calculated, which would seldom happen to be a positive integer. Neither of your columns appear to be grouping numbers.
% The Anderson-Darling k-sample test was introduced by Scholz and Stephens
% (1987) as a generalization of the two-sample Anderson-Darling test. It is
% a nonparametric statistical procedure, i.e., a rank test, and, thus,
% requires no assumptions other than that the samples are true independent
% random samples from their respective continuous populations (although
% provisions for tied observations are made). It tests the hypothesis that
% the populations from which two or more independent samples of data were
% drawn are identical.
This requires an input that tells it which population each sample is drawn from. The program uses column 2 of the data to hold that information.
Possibly you need a different test.
