the variable my has not the same data type like the column in your table.
Maybe, you need to convert the data-type like in the comment mentioned (e.g. str_to_num(...)).
what value you get, if you copy detailRes[colRes,rowRes] into expressions --> first column?
If colRes or rowRes is zero, you get the value of the index and this is every time of type string.
in the debugger (foot area) you have a tab expressions, there you can check the value of an expression. In the first row you can insert an expression (in your case: detailRes[colRes,rowRes] ), in the second column you see the value of the expression.
there was a problem in the Experimentmanager.
Do you have the possibility to update?
Which version of Plant Simulation do you used?