It's because you have to import the images to the stage first (Ctrl + R) and there you can select them all, right-click them and then choose Distribute to keyframes.
Optionally, if your files are named sequentially (ex.: image001, image002, and so on) you just have to select the first one and Animate will prompt you if you want to import the images as a sequence.
1 person found this helpful
EDIT: oh, nevermind! the issue has been fixed. thanks for your help!
if i import them to the stage then they are all pasted onto one keyframe. also, my files are named sequentially, but animate never gave me the option to import them as a sequence. (i select all from my files and click import, and it gives me a progress bar on how much has been loaded to the library. then it loads. nothing else happens.)