Vim's jumplist has always only one entry

I'm learning to use the jumps (CTRL-O, CTRL-I). But vim's jumplist allways has only one entry no matter how many jumps I make. Tried with /, ( and ). Anyone knows why ? I'm not loading any .vimrc.

Edit:

Explaining better how I'm testing this: I created the following text:

djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw. djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw.  djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw.  djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw.  djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw.  djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw.  djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw.  djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw.  djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw.  djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw.  djklfhsadkjfh ksjdf hskadf hskldjfhwelkrj hewlkjrg hewkr ghlwekrjhg klevhw.

then I used $ to go to line end, then I used ( to go some phases before. In :h jumps, I read that ( is a jump. But when I see jump list (:jumps) after the (, there is only 1 jump all the time.

If that example text is one single line, only one jump is recorded. A jump has to go to a different line to appear in the jump list. You can also explicitly record a jump point via m', but also only one in a line.