I took a look. You're using embedded macros. That's what the book is suggesting you do? I suppose that's one way to begin learning but I haven't used any macro save for AutoExec in so long that I no longer know how to create or edit them beyond what an AutoExec usually does. Most of us only use code as macros are too limiting. You may not be too eager to learn code, but consider that eventually you will likely migrate to code and all the time you spend learning macros might be a waste.
You can turn on single step option, open form again and click, then you'll step through and can review the conditions. I did that and added a couple of parameters (form name and object type) to no avail. Hopefully we have a macro savvy person lurking here. Seems to me that the error condition (<> 0) is false but I don't know why.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.