keyword motionSolver is undefined in dictionary "/home/ming/study/4cylinder_vortex_sh
 

When I finsh the moveDynamicMesh,I just want countine .I input
pimpleFoam | tee log.solver.
It not work.
keyword motionSolver is undefined in dictionary "/home/ming/study/4cylinder_vortex_shedding/c26_Re200_pimpleFoam_MovingCylinder/constant/dynamicMeshDict"

file: /home/ming/study/4cylinder_vortex_shedding/c26_Re200_pimpleFoam_MovingCylinder/constant/dynamicMeshDict from line 17 to line 28.

And my dynamicMeshDict file is
dynamicFvMesh dynamicMotionSolverFvMesh;

motionSolverLibs ("libfvMotionSolvers.so");

solver displacementLaplacian;

displacementLaplacianCoeffs
{
diffusivity inverseDistance (cylinder);
}

Please help me：困惑：