Activity indicator not showing sometimes in android

Hi I have created a chat application,which is using tableview,I have added a activity indicator in it.but some times it is not working.Here is my code please help,

var sentFile = Ti.UI.createImageView({
                                    image:imgPath,
                                    id:'sentFile',
                                    left:'28%',
                                    width:'80dp',
                                    height:'80dp',
                                });
 
                                patDocRow = Ti.UI.createTableViewRow({
                                    color:'black',
                                    height:'95dp',
                                });
                                patDocRow.add(sentFile);
                                var leftChatter = Ti.UI.createImageView({
                                    image:imageUrl,
                                    left:'1%',
                                    width:'80dp',
                                    height:'80dp',
                                });
                                patDocRow.add(leftChatter);
                                var progressView = Ti.UI.createView({
                                    backgroundColor:'transparent',
                                    height:Ti.UI.SIZE,
                                    width:Ti.UI.SIZE,
                                    left:'52%',
                                    top:'5dp'
                                });
                                var activityIndicator = Ti.UI.createActivityIndicator({
                                  color: 'green',
                                  // font: {fontFamily:'Helvetica Neue', fontSize:26, fontWeight:'bold'},
                                  // message: 'Loading...',
                                  style:Ti.UI.ActivityIndicatorStyle.DARK,
                                  top:10,
                                  left:10,
                                  height:Ti.UI.SIZE,
                                  width:Ti.UI.SIZE
                                });
                                progressView.add(activityIndicator);
                                patDocRow.add(progressView);
                                activityIndicator.show();
                                tableView.appendRow(patDocRow);
                                tableView.scrollToIndex(tableView.data[0].rows.length);