Without the exact error message nor your version of outlook, here is a generic answer.

Repair your forms cache. Tools-Options-Other-Advanced-Manage Forms.


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Milly Staples [MVP - Outlook]

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After furious head scratching, Highrevving asked:

| For no apparent reason when I try to add a new appointment to the
| calendar the system says that the form is not available and to
| contact my administrator. As I am the only user I don't know what to
| do. Updating from my PDA doesn't work either.