NJ Online Casino Anomoly

I live in NJ and we have legal online Casinos. One of the Casinos that I have tried seems to have some quirks. First off every time I win close to the amount that I have deposited I suddenly can not win and lose the winnings and the deposit. It does not matter if I deposited twenty dollars or two hundred dollars. I am playing Roulette and I know I should take my winnings out when this happens and call it quits for a while. However, I keep going and if I am betting on Red or black or two of the dozens, the outcome will be opposite my bet. It has gone on a streak of about ten of the dozens and if I suddenly change my bet to include the dozen that has been coming up one after another, it changes to a the dozen that is not one of the two I have chosen. Now I have practiced with 5000 spins in the demo mode and the most times I saw that one of the dozens would come up in a row was five. Suddenly I start to play with real money and things change and once I am getting close to doubling m money, which is about a thousenad or so spins, the software acts up and I lose cosnstently one time after another, say twelve times in a row at which point I am busted.

My question is why do things look so good with about 5000 spins that I kept track on some excel graph sheets when playing in Demo mode and then suddenly go to pot when I switch to real money in say 1000 to 2000 spins?

I read on one web page that the RNG for the Roulette Online Game is like a Slot Machine RNG and is harder to beat than a real Roulette Wheel that a Dealer is releasing the ball/ I have had the same bad luck using the Basic Single Deck and Multi Deck Strategies at the Online Blackjack Game at Virgin Casino? I have to learn to take my deposit and small winnings out before I hit the lose streak that hits all the time.

Has anyone else had a similar experience with the Borgata, Betfair and Virgin Online sites that are all approved for NJ gambling as long as you are in the state.

Thanks for any advice you can give.