Unable to create video in Kling

It's impossible to create a video in Kling. I'm doing everything correctly: writing a prompt, uploading the first and last frame, but Kling models won't create videos. Other models work fine, with the same parameters. But Kling doesn't work, it just gives an error and asks to try again later. I only managed to create a video in Kling once, even though I've been trying all day. I'm talking about all Kling models; none of them work.