Why does the chart study line have a dashed/dotted line on it?

The solid study line becomes dashed when there is not enough data loaded in the chart to properly display the study period. For example you have a Moving Average study and the period is 200 on your chart but you see a dashed line on the left of chart. In this case, you can click on the left edge of the chart, the cursor becomes a left-facing arrow and you will be able to load more data, then you can zoom back in with the + and – and the line will show solid.