Custom brush set eraser mode. Bug or user error?

Hi. I want to make an action to toggle the eraser mode on/off for the custom brush. This is the whole script...

Code:

---

<Header>
    // === Author data
    Author Name: ""
    Script Name: "Test Lab"
    Comment: ""
    Script Type: ""
    Script Feature Flags: 0x000000000
</Header>

// I got this command from recording a script
EvType: Command        CommandID: SetToolProperty        ParamType: ToolProp        Value: { 0x0B2D0609D (Eraser Mode), 1 }

---

When I run the action, I see the eraser mode switch on briefly but then it immediately turns off again. Am I doing something wrong or is it a bug?

edit: Using Vitae
edit again: I know that this code just turns it on, not off. One step at a time.