Why does a mutual fund's NAV fall when it distributes dividends/capital gains?

I have chosen to reinvest my dividends, but how come the NAV does not go up? For example if I recieved $1,000 in distributions how come the NAV does not go up, since I would technically be purchasing more shares? Doesn't the price go up when more money is invested in the fund? How is it different than if I invested $1,000 of my own money?
Thanks.

Take it in steps....NAV is called the Net Asset Value of the fund. If the Fund has 100 shares and all of the underlying investments in the funds are worth 1000 dollars then the NAV is $10. Now if the fund is required to pay out capital gains/dividends of $50. Then the fund is now worth $950 and the 100 shares have a NAV of $9.50. Now, if you reinvest that dividend/capital gain (not everyone does) then you buy back shares at that $9.50. The $50 is able to buy back 5.263 shares. Now the fund is again worth $1000 but there are 105.2632 shares. NAV remains at $9.50 but the overall value of the funds is that $1,000. If you follow the trail you can see that you didn't really lose any money...the share value dropped but your shares increased the same ratio. Any difference between that price is the normal NAV fluctuation for that day.

adding money to the fund wouldnt make the price go up, the fund just issues more shares, it doesnt increase the nav

if the stocks in the fund go up,then the nav goes up, personally i never look at the nav. i just look to see what my money is doing

nav goes down as it is paying out assets. Your number of shares goes up if you reinvest so you are even. If went up when you reinvested you would get fewer shares & lose.

I believe the NAV doesn't go up because you're issued with more units. You have more unit at the same value. You're getting wealthier, no doubt. It's like going to ATM. Say you have 1100. All of them are in the bank. After you withdraw 100, your wealth will still be 1100. The difference is you have 100 in your wallet and 1000 in the bank. With the mutual funds, instead of having 100 units worth 100,000, after the distribution you have 101 units worth 101,000. Each unit will still worth 1,000. You just have more of them. If you invest the 1000 yourself, you would have 100 unit worth 100,000 and 1000 worth of whatever you invest in.