Have never used or heard of that mud. Now are the seams your talking about in the corners or are they your flats. If it's your flats then was your fill and first coat hot mud? If it was then it sounds like maybe you put it on to thick. If the problem is the angles then the mesh is the problem, it doesn't have a crease like paper so it is almost impossible to get good corners. also it is very easy to cut with your knife when you are mudding. Therefore losing it's strength. Maybe you just use a light weight mud for every coat. There are many things could cause this a few more details would help.