I installed and activate mega menu.
However, it turn out that all the 1st row appear vertically instead of horizontally.
In the Main menu, it should appear as:
Item 1 Item 2 Item 3
Item 1.1 Item 2.1 Item 3.1
Item 1.2 Item 2.2 Item 3.2
But it appeared as:
What went wrong with the installation? Please advice.