Probably a conflict with some other program that also hooks into games.
If you haven’t done so already, please first try the trouble shooting options that pop up in vorpX’s ‘Attaching To…’ dialog after a minute. Install a hook helper or switching to alternative hooking can often help to resolve hooking issues without having to get to the bottom of the matter.
If that doesn’t help or you don’t see the dialog at all, you have to dig deeper. The pinned trouble shooting post on top of this sub-forum has more details on the matter.