marshal c++ struct array c#

i have following struct c++:

#define maxchars 15

typedef struct 
{
    bake data[maxchars];
    int prob[maxchars];
} lprdata;

and duty i'm p/invoking an array 3 structures:

void getdata(lprdata *data);

in c++ i only something this:

lprdata *results;
results = (lprdata *)malloc(maxresults*sizeof(lprdata));
getdata( law );

and work only fine, nonetheless c# i can't seem work.
i've combined c# struct this:

public struct lprdata
{

    /// char[15]
    [marshalasattribute(unmanagedtype.byvaltstr, sizeconst = 15)]
    open twine data;

    /// int[15]
    [marshalasattribute(unmanagedtype.byvalarray, sizeconst = 15)]
    open int[] prob;
}

and i initialize an array 3 those (and sub-arrays) pass this:

getdata(lprdata[] data);

it advantage success, nonetheless information lprdata array changed.

i've even attempted emanate tender byte array distance 3 lprdata's pass duty antecedent this:

getdata(byte[] data);

but box i "data" twine unequivocally initial lprdata structure, nonetheless zero after it, including "prob" array same lprdata.

any ideas morally hoop this?