The language does not support overloading, but various folk have suggested alternatives. Try googling for "actionscript overloading".
can u explain the reason?
ActionScript aims to follow the EcmaScript 4 language specification which does not include method overloading. The two have diverged somewhat because EcmaScript 4 is still in a proposal stage and is subject to change. Read more here:
A proposed EcmaScript feature called generic functions may offer capabilties similar to method overloading. It is possible such a feature may find its way into ActionScript 4, but I'm not aware of any official announcements to that effect.