Item_Data_Line:= mylist
This is your problem line. Item_Data_line is a string (Ansistring). mylist is a TStringlist. You're trying to assigned one to the other, and they're different types, so the compiler is correctly complaining.
As shown by others in their posts above, in your code snippet the correct line should be
Item_Data_Line:= mylist[x];
Item_data_Line is a string. mylist[ x ] returns a string. Everything matches, compiler is happy :-)[/s]
UPDATE: BAH, Ignore this. I see you are in fact using [ x ] in your code, you just didn't wrap it inside a [ code ] tag in your post, and the forum code mapped [ x ] to a bullet point. (You'll see I've added extra spaces so the the forum code doesn't get confused)
Can you post your full code, and wrap it inside [ code ] tags? I want to see what Item_Data_Line is declared as.
Many thanks