meta slider image can't upload

i have installed free version of meta slider lite to my site but when i tried to upload image by click on add slide button it gave me an option to upload image i have select a PNG image it start uploading with upload bar but on bar completion it generate a red label error and a message uploading error please try again later.tell me please what should i have to do.
edit i think problem with my theme i’m also using my own created theme when i switch theme it will work perfectly anybody can help me to what i have to do with my theme to make it operational with meta slider.