Why did Scots not act on a key part of Declaration of Arbroath?

Source::
The National
Why did Scots not act on a key part of Declaration of Arbroath?

SEVEN hundred years ago this week, on April 6, 1320, the Scots wrote a letter to Pope John XXII which became known as the Declaration of Arbroath. In this affirmation of Scottish independence, the signatories announced they had chosen Robert the Bruce to be their king and would resist all further attempts at conquest by the English.

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The National
Why did Scots not act on a key part of Declaration of Arbroath?