做正挤压时又遇到一个问题!

请大家指点这是什么错误，应该如何避免？
*** INFO: Begin of Simulation for Run# 18
Starting time is:Fri Mar 07 12:17:02
*** INFO: End of Simulation for Run# 18
FEM MESSAGE:
Candidate Rocking motion is detected
34 0.4276578445E+02 0.1105917720E-01 0.6681240367E-02 0.391 R
35 0.4274229324E+02 0.1106489016E-01 0.6667521708E-02 0.359 R
36 0.4276578357E+02 0.1105917728E-01 0.6681216798E-02 0.407 R
37 0.4274229323E+02 0.1106489050E-01 0.6667509870E-02 0.359 R
38 0.4276578357E+02 0.1105917711E-01 0.6681217334E-02 0.328 R
39 0.4274229323E+02 0.1106489040E-01 0.6667509840E-02 0.375 R

Candidate Rocking motion is detected
It may result from insufficient boundary conditions
Ending time is:Fri Mar 07 12:17:30
*** INFO: Simulation Module Indicates End of Simulation
*** INFO: End of Automatic Remeshing Run -- Bye###
Total Number of Runs = 18