What's the deal with (display:) and computed values?

Hi everyone, I only post as a last resort. This is driving me insane.

the code: (set:$Selection to "(Print:($Options's 1st's Page))") $Selection (display:$Selection)

evaluates to: "Conversation-DoNothing" then error: I can't (display:) the passage '(Print:($Options's 1st's Page))' because it doesn't exist.►

What's up with (display:) and computed values? how can I get around this and have it display the passage "Conversation-DoNothing"? What causes this?

If I write: (set:$Selection to (Print:($Options's 1st's Page))) $Selection (display:$Selection)

It comes up with: Conversation-DoNothing (display:)'s 1st value is a (print:) command, but should be a string.►