Apple Iphone 6 Backup To Icloud

My iphone 6 will not backup to icloud. i have got backup turned on in settings > icloud > backup but it says that the last backup date was 13th january (over two months ago).. When i checked in settingsicloudstoragemanage storagethis iphonelatest backup was shown as incomplete i have deleted backup (on the same page on the bottom) since that, i