Good morning

I done a 90 day report online for the second time as before always just went into the immigration office to do before that. The first one went through no problem but this time it's been rejected for some reason. I done everything exactly the same so I cannot understand why !!! . I'm on a non O retirement visa and it's still valid til May next year. The due date was 26th September and I done on the 27th. Has anyone had the same problem? Any advice would be gratefully appreciated