Issue filling with color between two lines in graph

Thank you Sergei. I much appreciate you sharing that link. I've seen that explanation, as a number of others as well. However, unless I missed it, it does not deal with my issue. I do not need to color between two lines for the whole domain of the horizontal axis. Only for a series that covers a part of it. Let's say the chart has 100 periods. And that I need to color between two lines that start in period 30. There is some coloring going on between period 29 and period 30 that I would like to remove. That's what I've marked in the picture I attached to my post. The examples I've seen do not run into this issue because they color for all 100 periods (or observations) and, therefore, this issues does not arise. If anyone knows how to deal with this I will appreciate the help. -NC