As noticed by 'user3772045' on stackoverflow.com [1], the `getResultString("Column", row)` returns `null` when run on a results table that was opened from a file.

The following macro reproduces the issue:

    row = nResults;
    dir = getDirectory("temp");

    setResult("String", row, "xyz");
    setResult("Number", row, 5.0);

    // get results from new table
    print(getResultString("String", 0));
    print(getResult("Number", 0));

    saveAs("Results", dir + "Results.xls");
    open(dir + "Results.xls");

    // get results from re-opened table
    print(getResultString("String", 0));
    print(getResult("Number", 0));


On a related note, repeated runs of this macro (with the results table open) result in unexpected behaviour: a new "String" column is created, and the string and number values get filled into the wrong columns.

Cheers,
Jan

[1]: http://stackoverflow.com/q/32468347/1919049