关于用zlibwapi.dll进行字节数组压缩的问题

我根据别人写的用vb调用的代码，进行改装到c#里面，但是会报以下异常：
Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
vb代码如下：

End Function

c#代码如下：

[DllImport("kernel32.dll")]
        public unsafe static extern void CopyMemory(IntPtr hpvDest, IntPtr hpvSource, int cbCopy);
        [DllImport("zlibwapi.dll")]
        public unsafe static extern int compress(IntPtr dest, int destLen, IntPtr src, int srcLen);
        [DllImport("zlibwapi.dll")]
        public unsafe static extern int uncompress(IntPtr dest, int destLen, IntPtr src, int srcLen);

        private const long OFFSET = 8;
 private void button2_Click(object sender, EventArgs e)
        }