my lo wont sleep

my lo is 9 months old. recently she keeps waking up abt 12plus to 2plus just to play. before that when she was fidgeting i hugged her and pat her back to sleep. she fell asleep in my arms and once i put her down she will scream. i tried patting her and all but she just wont go back to sleep. does anyone know why? this has been going on for a week and its super frustrating