Problem with adaptive mesh
 

while running a calculation with adaptove mesh, I got the following error message

Refiner 11.0 [2007.08.08-23.01]
Adaption step 1 of 3.
8415 prismatic stacks have been identified in the original mesh.
Maximum height = 6
Minimum height = 6

Marking elements for coarsening and refinement:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Number of elements initially marked for refinement: 17947
Number of elements removed because:
They already meet the minimum length criteria: 0
They are in regions not marked for refinement: 0
They are already in the deepest refinement level: 0
There are not enough nodes available to refine them: -3951
----------
Number of elements actually marked for refinement: 13996
----------
Target number of nodes at end of step: 128041

+--------------------------------------------------------------------+
| An error has occurred in cfx5solve: |
| |
| The ANSYS CFX mesh refiner could not be started, or exited with |
| return code 255: . |
+--------------------------------------------------------------------+


Could someone tell what is wrong in my model? Thanks.