There is
a thread on this on this forum which gives you four reasons why Mussolini invaded Abyssinia - I think you have already checked it out.
In addition, why don;t you try a forum search on:
+Abyssinia +Mussoliniand chase some of the likely-looking links.
A google search on
Why did Mussolini invade Abyssiniapulls up a number of other websites offereing ideas, including a short explanation of this on the
Learning Curve.