求助ABAQUS模拟螺栓连接！！

各位大神，新手求救。。要求做一个挂墙架的螺栓连接分析，简单分割了一下几何元素画网格，求解的时候为何一直显示The volume of 16 elements is zero, small, or negative. Check coordinates or node numbering, or modify the mesh seed. In the case of a tetrahedron this error may indicate that all nodes are located very nearly in a plane. The elements have been identified in element set ErrElemVolSmallNegZero.