@pleasures
i therefore checked his team and there were players at the right 99 level, but whay arent they showing on my list?

I wrote about this here
Remember that it’s not only the prerequisite of the lv and server but also the fact that only a smaller group of those managers is able to see your player in the list. There is some rotation too.
Another manager can see your player in the list today but not in the next 2-3 days and see him again after that.
Also there are some hidden sub-groups. Meaning that a manager you know with the requirements of LV and server, might not ever seen your players in his nego list.
also can change from season to season