Discouraged by changing of tree

[KellyvanGils]

I started a year ago with learning some Spanish next to my studies, and in the beginning I was very active and I could see how much I improved every time. That was helpful, as it motivated me to go on.
However, now it shows that I did not complete the lessons when I come back to the site after two weeks or so. However, the previous time it said I did complete it. This is not motivating at all for me, as I would like to do it well and complete all the lessons before continuing with a new one, but this seems almost impossible.
Does it bother some of you also?