I am stuck with a similar problem.
I have a string in the list and trying to assign it to the row of a data table. I get an erroe saying - "Cannot set value for column beacuse row number is invalid".
Param = {};
Param = Concat items({A, B, C,D}, " ");
dt = New Table( "RAWDATA" );
dt<< New Column( "Line", Character);
Column(dt,"Line")[1] = Param;