Help Fixing Leak

[Digger]

I just installed a softener and whole house filter. I tapped into the main pipe coming from my well. All the joints are fine except 1. I have copper piping then I connected a piece of flex hose that runs to the softener.

Where I screw the mailers end ofthe flex hose to the female end of the copper pipe is a small leak.

I took it apart reapplied teflon tape screwed it back in and it leaked. I replace the flex house with a new one tefloned it again and about 15 minutes later small drops of water appeared and it started leaking.

I am using the same flex pipe on the other side of the softener and no leaks.

What the heck is wrong? What did I miss or how can I fix it?

I wanted to include a picture but there doesn't seem to be away to attach while using my phone

Your help is greatly appreciated in advance.

 

[frodo]

use pipe dope not teflon tape

 

[Ewhitaker0020]

use pipe dope not teflon tape

I have a question... Are there actual applications that require pipe dope over Teflon tape or vice versa? I didn't have any luck using pipe dope on my water connections when I redid my main water supply. I had one that kept leaking so I ended up using Teflon tape and it fixed the leak. My water pressure is fairly low about 30 psi.

So do certain connections warrant one over the other? Or is it more of a try one and if it leaks try the other type of situation?

 

[havasu]

Rectorseal #5 is my go to product.