(Explaining estoppel can sometimes become confusing, i found this online and maybe it will help)
(estopped) A bar which precludes someone from denying the truth of a fact which has been determined in an official proceeding or by an authoritative body. An estopple arises when someone has done some act which the policy of the law will not permit her to deny.
In certain situations, the law refuses to allow a person to deny facts when another person has relied on and acted in accordance with the facts on the basis of the first person’s behavior.
There are two kinds of estoppel.
Collateral estoppel prevents a party to a lawsuit from raising a fact or issue which was already decided against him in another lawsuit. For example, if Donna obtained a paternity judgment against Leroy and then sued him for child support, Leroy would be collaterally estopped from claiming he isn’t the father.
Equitable estoppel prevents one party from taking a different position at trial than she did at an earlier time if the other party would be harmed by the change. For example, if after obtaining the paternity judgment, Leroy sues Donna for custody, Donna is now equitably estopped from claiming in the custody suit that Leroy is not the father.
An example of the slowly disappearing tendency of the legal profession to speak in secret code. All it means is ‘stopped,’ ‘blocked’ or ‘not allowed.’ Not only is it bizarre but the term does not appear to originate in any known language. Our research indicates it started either as a legal fraternity’s drunken prank or was the result of an unknown Judge’s severe speech impediment. —the word estopped originated from middle french “1575–85; < Middle French estoupail stopper. See estop, -al2"