How to reduce alpha value of movie clip using code

Hi everyone

I am trying to reduce alpha value of movie clip. but it doesnt work some code i tried which given below. I want it using code only.
onClipEvent(load)
{
alphavalue=100;
for(i=0;i<=100;i++)
{
_root.almc._alpha = alphavalue;
}
alphavalue–;

}

Please help me
waiting for reply.

thanx in advance
best regards,