The grid’s “Field for Item Data”, as set in the grid’s properties, is the only field which can be directly referenced from another prompt. After you have moved off the grid prompt, the other grid column values are not available, cannot be directly referenced; they must be set to variables and the variables then referenced.

Also, the GetIndex function will not work after the program has moved off the grid prompt. If you have a Static grid and need to save the selected grid column value, create a hidden textbox element and set the value to that element.