Show your code, it is impossible to figure out why it is doing that otherwise

Yes. Show a simplified view of your code, if it is too long.

Ha ha, yeah I know. Kinda blanked when making up names

"Horizontal" inheritance examples abound when doing a search for it.
By "horizontal" I mean lotsa children classes which extends a parent class.

However, "vertical" inheritance is almost impossible to find or it is not explicitly explained if such kinda arrangement is possible in Java .
By "vertical" I mean a sequence of class inheritance in which a child class is derived from a parent class, which in turn, is also derived from another parent class and so on and up!

Like the asimes's example of class Bed extending Bedroom, and in turn, extends House, the "granpa" of Bed. 

What's prohibited is having a class extending 2 or more parent classes!
But most explanations we find online have very poor & confusing phrasing which lead us astray.
Like this very one example from Processing's reference:

"Note that in Java, and therefore also Processing, you cannot extend a class more than once. Instead, see implements."

Reading something like that, We are led to understand that "vertical" inheritance is not possible.
But knowing what I know now, I realize the above "explanation" rather refers to the forbidden usage of extends to more than 1 class at once!

Seems like Java class reproduction is asexual!  

I thought you might be interested in seeing the inheritance hierarchy for the G4P library. The grey box is the base class for all the controls and it implements the interfaces on its left and the classes on the right are subclasses. You can see that each class can only have one parent but a parent can have many children, but a class can implement many interfaces.