Trial Version message

I use FileVistaControl with license key.
Year it worked fine, but now displays the Trial Version message. Why it occurs?
May be it depend from security steings or firewall settings?

This shouldn't happen, maybe you changed the key by mistake.
I have resent your original key via email.

It same key what i use. 
Is some else idea?

Are you sure you copy/paste the whole key, note that your key ends with "=" sign.
What's your FileVistaControl version?

Yes i'm sure
Version - 1.5.7.0

Please send the code snippet or page code where you add the control and set the license key so that we can see if anything is wrong with the code.