.class file leads to Fundamental mode, no disassembly

[Reissner]

I run emacs 27.1 and have installed autodisass-java-bytecode 1.3.
I expect that if opening a .class file, some java mode or disass mode is entered
and i can see some java sourcecode.
Instead I see mode 'Fundamental' and the file displays as a bulk of strange characters.
Means: not disassembled.

I am aware that I do not provide enough pieces of information, but just let me know what you need.

[gbalats]

Is javap installed? Can you disassemble a .class file manually with it? If it's not on your PATH, you should tweak the variable ad-java-bytecode-disassembler to make it point to the absolute path of javap.