I figured it out. I'm not sure why I can't read the reply by Charles Kenyon,
maybe he came to the same conclusion.
This problem occurs when Macro Protection is enabled and you choose Disable
Macros when the form document is open in Microsoft Word. This problem can
also occur if your security settings are set to High in Microsoft Word.
To work around this problem, change the security setting in Word, and then
reopen the document. To do this, follow these steps:
1. On the Tools menu, point to Macro and then click Security.
2. On the Security Level tab, click to select a security level other than
High. It is recommended that you select a security level of Medium.
3. Click OK to close the Security dialog box.
4. On the File menu, click Close to close the protected document that
contains the Control Toolbox control.
5. On the File menu, click Open to open the protected document.
6. If you selected Medium as your security level in step 2, a warning dialog
box appears, indicating that the document contains macros. Click Enable
Macros.
7. On the Tools menu, you can now select Unprotect Document.