I've checked again the MAL_GetStatus() at mass_mal.c and seen that I've overlooked that the calculation of Mass_Memory_Size is hard coded and depends not on the variable lun.
After change of e.g. Mass_Block_Count[1] = NAND_ZONE.... and so on into Mass_Block_Count[lun] = ..., Mass_Block_Size[lun]..., everthing works well. Means my problem is solved.. Regards Achim