Thread sealer on brake lines?

[FrozenNorthman]

Hey guys, this is my first time posting, this is quite the site you have here! I just replaced the brakes lines from the booster(is that right booster? not the master cylinder, but the secondary unit mounted on the drivers side, right near the firewall) to the calipers, including a new flex hose. when I pump the brakes, all I get is a gurgling sound, and fluid leaking from where the line meets the flex hose. my question is, should I be sealing this somehow, or will the fluid just eat the sealant? are there any other possible causes Ive overlooked?

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