Convert number into byte...

 This is the first time i write in this forum so let me see if it's usefull :)
 I have a problem using FJ Core to convert image into byte.
 
I have a code written in C# which works fine.
The problem is when im running it in VB i get the exception: Arithmetic operation resulted in an overflow
It works fine in C# to convert a negative number into byte For Ex. (byte)-90024  = 88
But when i try to do it in VB i get the exception.
raster(0)(column, row) = CByte((pixel >> 16))

raster(1)(column, row) = CByte((pixel >> 8))
raster(2)(column, row) = 
CByte(pixel)< ...