I have a function in C that returns an array of pointers in a parameter

NAGR(
OUT OB_R ** pprResources,
OUT int * pnNumResources
)

No matter how I marshall it, i only get the first element of an array
of 6. I get the first element quite well with all its data correct, but
my array of pointer does not return any other element...

I'm marshalling like this:

[DllImport("whatever.dll")]
public static extern int NAGR(
[In,Out, MarshalAs(UnmanagedType.LPArray,SizeConst=6)]
IntPtr[]  pprResources,
out IntPtr pnNumResources
);

Then in my code i'm retrieveing like this:

p=NAGR(rrr,out j);
if(p==0)
{
for(int iii=0;iii<j.ToInt32();iii++)
{
oo = Marshal.PtrToStructure(rrr[iii],typeof(OB_R));
}
}

After that, only rrr[0] has a valid OB_R structure, the rest is empty,
and i'm sure that there are 6 elements.
Any info will help

Thanks

David