Your problem is that one data source or the other needs to have dates for *all* periods in it. This data source becomes your primary data source and will plot all 15 periods. At this point data blending will be useful because there will be matching fields to "relate" against.
I know this isn't the behavior that you want, but I want to make sure it makes sense.
Hy Russell, you right thank you.
That is why my chart was disconnected, thank you.