[petsc-users] Get grid sizes from DMMG finest grid in Fortran

[El Hombre Frances]

Hi,
I'm looking for how to get information about the DA of a DMMG finest grid.
I saw that you can access them with
call DMMGGetDA(...
call DAGetInfo(...
but it doesn't work in the main program, i get this error
0]PETSC ERROR: Invalid argument!
[0]PETSC ERROR: Wrong type of object: Parameter # 1!

I tried with this example
http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/src/ksp/ksp/examples/tutorials/ex22f.F.html

I don't know how to get DA infos outside the subroutines ComputeRHS and 
ComputeJacobian

I want grid size of the DA 3D in order to plot the field. I noticed that 
it's possible with PetscObjectQuery in C language.

Thanks for your help

Pierre Navaro