My is not firing java bean method

Question

My JSF code am trying to perform a action with commandLink

but my bean method not called when i click on commandLink but page is reloading.

My jsf commandLink code and am calling java method.

   <h:commandLink title="#{a.string}" 
value="#{a.eventString}" 
action="#{a.viewReport}" style="margin-left:11" >                                                </h:commandLink>

My java method to open a file with selected value

        public String viewport() {
                log.error(":::::::::::::::::123123123123123");
                if(DetailsTable != null) {
                        selected =  (Aly) DetailsTable.getRowData();
                        return "report.view";
                } else  {
                        return null;
                }
        }