Migration is not happening in PlanetLab Examples any specific reason?

[Riman-M]

Experiment name: 20110303_lrr_mu_1.2 Number of hosts: 800 Number of VMs: 1052 Total simulation time: 600.01 sec Energy consumption: 5.87 kWh Number of VM migrations: 0 SLA: NaN% SLA perf degradation due to migration: NaN% SLA time per active host: 0.00% Overall SLA violation: NaN% Average SLA violation: 0.00% Number of host shutdowns: 800 Mean time before a host shutdown: 591.01 sec StDev time before a host shutdown: 51.21 sec Mean time before a VM migration: NaN sec StDev time before a VM migration: NaN sec Execution time - VM selection mean: 0.00000 sec Execution time - VM selection stDev: 0.00000 sec Execution time - host selection mean: 0.00200 sec Execution time - host selection stDev: 0.00141 sec Execution time - VM reallocation mean: 0.00050 sec Execution time - VM reallocation stDev: 0.00071 sec Execution time - total mean: 0.00600 sec Execution time - total stDev: 0.00283 sec