XMR balance never added

"when a block was found , every worker should got his reward, even a very small part"
Technically this is not always true. Read the FAQ, look for round 5. Although this would not be your case if you were constantly mining for over a week, so you would fit in the share window. Can you confirm you started mining before the block was found? What is your hashrate? Also what is your wallet address so we see what you are seeing?

my PCs are not new, but constantly connecting to pool

my sat shows hashrate 13h/s, shares 4.87M and balance 0

address 486bSS25BcwdMR4tBXGTzYaECJiH8i7E9BTbLAUaJna74Ty1UwAKKzdWbwaVe4vUMveKAzAiA4j8xgUi29TpKXpm3yJmHmm

thanks

13H/s ?  You're looking at less than 0.0007 XMR per week with ideal conditions.  And the minimum payout of 0.1XMR would take you about 143 weeks to get (again ideal conditions).

Electroneum is probably going to get you more regular payments (once blocks start to be found), but I doubt your returns are going to cover your electricity costs.

Yep, Ben beat me to it. With that hash rate, your balance is certainly less than 0.001, which is the minimum balance to be displayed on your stats sidebar.

thank you for replying, this pool is one of my minings. still finding which one is the most effective.

Are you mining with a cell phone or something? I am getting 500 hash with my Ryzen 1600 CPU. I can't imagine intel i5's or, what i3? I can't imagine such low hash rate.

mining with some old pc and nb

maybe AMD cpu is not a good choice for XMR mining.