Panel does not accept orders

[malder]

When a customer clicks the link of the order - appears a form. He fills it, input captures, presses to send a request,but again there is an offer of the order , not the message - like "accepted. check your email"
Few times it worked.
There is no any email with notification sent on my account or customer's.
Can you please tell what could be the problem?

PS. Users adds through the the admin panel. All the rest works good.