FORGOTTEN SCREEN LOCK PATTERN RESET (With Google Account)
If you have already set up a Google Account on your tablet and locked yourself out by forgetting the unlock pattern you should be able to get back in by attempting patterns six or more times in immediate succession - after which it should ask you to enter your Google Account (remember to put the @gmail.com on the end!) and let you in. There is also an Unlock Page for Google Accounts (I don't personally know exactly how this works) but it's supposed to be an alternative if the device isn't asking for your account info.
Despite the fallbacks/safeguards it is still possible (especially on unofficial/unsupported devices like our tablets) to be locked out. This is also the case if you bypassed the Google Account setup and subsequently locked yourself out of the tablet, which would have no Google Account associated with it yet.
Maybe this helps you.
Else maybe you can try a factory reset?