if you have any clu or experience i would apriciate some help 
her we go again 
here we go again 
i get an compiler error that it cant find the size of the structure 
in this rutine 
buf = new byte[Marshal.SizeOf(dmh.imageInfo)]; 
if i mark out this from the structure it works 
[MarshalAs(UnmanagedType.LPStruct, SizeConst=8, ArraySubType = UnmanagedType.LPStruct )] 
DpxChannelInformation[] channel; 
so i think it cant find the size of this structure because it have an array od structres 
public struct DpxImageInformation 
{ 
UInt16 orientation; 
UInt16 channels_per_image; 
UInt32 pixels_per_line; 
UInt32 lines_per_image; 
[MarshalAs(UnmanagedType.LPStruct, SizeConst=8, ArraySubType = UnmanagedType.LPStruct )] 
DpxChannelInformation[] channel; 
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 52)] 
string[] reserved; 
}