It is the secretary who should compile the agenda.
In many cases the strata manager acts as secretary and this can be done under delegated authority from the owners corporation.
You need to find out if the OC has given the strata manager delegated authority to act as office holders on its behalf.
This is probably in the contract between the OC and the strata manager.
However even if the strata manager has the delegated authority to act as secretary, the elected secretary of the EC can at any time over ride the strata manager.
It depends who is compiling the agenda. If the secretary is doing it then you have to contact the secretary, but if the SM is doing it, then you need to give it to him/her.
Also bear in mind that there are time limits. You need to find out the deadline for submitting motions.
It sounds as if there is a break down in communications here. Perhaps who is doing what needs to be sorted out.
Good Luck!