troubles with dimensions

Hi, I have problems when I add angular dimensions. I drew a 4 lines poligon (each side has a different length and I checked that the starting point of each line is the ending point of another) and when i add the dimension of the angle between two lines the other two lines move a little bit from their original position. why does this happen, how do I fix it?

There is a bug in V 2.1.3 where in angular dimensions the original lines seem to get lengthened. In fact these extensions are part of the dimension, you can see this if you click on these extensions, the whole dimension gets selected then. If you set the extension lines offset to zero in Current Drawing Preferences the issue disappears, but unfortunately this also affects normal dimensions. You can use fixed length extension lines as a workaround, if it suits you.
This issue is fixed in V 2.2.0 rc, so to upgrade is the best solution if you are on Windows.