Refresh Registry

Question

I have written a Windows Service in VB.Net. All this does is enables the ie proxy if a given gateway ip is found. The program seems to be setting the value, but is not updating the registry. I have tried the flush command and the Shell("rundll32.exe user32.dll, UpdatePerUserSystemParameters") command to no avail. Could someone please advise me on how to update the registry once values have been set.