Your method of adding values to the array is fine, but I think you are unclear on the concept of server side scripting.
Each time one of the links is clicked, your page is called all over again, <i>from scratch</i>. This means that your <i>$arrayselectionagttype[]</i> array is empty <u>every time</u>! At most, you will never have more than the last item clicked in that array.
If you want to have that array <b>persistant</b> from one page execution to the next, you will have to store it in a db and use sessions, or serialize it and store it in a cookie on the visitors machine so it is available with all its accumulated values each time the page is called.
HTH
-- Rich