DDEOPEN.EXE not opening document

[logician1989]

I am using TextPad 7.0.9 (32-bit) under Windows 8.1.
When I run this command:

"C:\Program Files (x86)\TextPad 7\system\DDEOPN32.EXE" TextPad.dde abc.txt

a new instance of TextPad opens (even if one was already running), and a dialog box window pops up. The title of the window is "DdeOpen Error", and it contains the message "Server TextPad.dde is unavailable".

Interestingly, the dialog box window remains, even if I close the TextPad instance that DDEOPN32.EXE started. The dialog box window has to be closed separately.

The exact same command, running under Windows XP, Vista, and Windows 7, causes TextPad to open the file "abc.txt" (without starting a new instance, if one was already running).

What must I do to get "Server TextPad.dde" to be "available", for DDE purposes, in Windows 8.1?

[bbadmin]

That dialog box is displayed by DDEOPN32.EXE when its DDE messages to TextPad are not acknowledged. The most likely cause for this is another process blocking the messages, such as a debugger. Try closing other applications until the file opens successfully.

[logician1989]

I know of no other applications I am running that would block DDE messages. I am not running a debugger. Even if I reboot my computer and run my TextPad-dependent application as the very first thing I do when the computer starts, I still get the message that "Server TextPad.dde is unavailable".

As I said, this doesn't happen in Windows XP, Vista or 7, but on this computer I am running Windows 8.1. Have you verified that DDE messaging works in Windows 8.1? Is it possible that Windows 8.1 has DDE messaging blocked or disabled by default?

It's not very helpful to say "this is most likely caused by something else; try things until it works." I've been trying on and off for a month; it doesn't work. Help!

[husby_d]

I just did a fresh install of Textpad 8.0.1 (64 bit) on a new machine (windows 7).

When I type the following from a command prompt:
"C:\Program Files\TextPad 8\system\Ddeopn32.exe" TextPad.dde a.a
I get a popup that says:
"Server TextPad.dde is unavailable"

I traced this to a bug in the Textpad installation.
In the registry, change this key:
[HKEY_CLASSES_ROOT\TextPad.dde\shell\open\ddeexec\application]
@="TextPad.7"
To
[HKEY_CLASSES_ROOT\TextPad.dde\shell\open\ddeexec\application]
@="TextPad.8"