How are you doing the signature?
Following the account generated in the example from the docs https://docs.substrate.io/reference/command-line-tools/subkey/
You can create a signature of a message:
echo "blabla" | ./target/release/subkey sign --suri 0xc8fa03532fb22ee1f7f6908b9c02b4e72483f0dbd66e4cd456b8f34c6230b849
It gives you this result:
c4273e58b19b582330577f380041171d7aa9def2922e492e1b5510bc17a03f3fe19ae2b4f8089a7b4ba821fabffb97596245aa6caecf686a9ff119010374af8f
That then you can validate with its corresponding account: 5Gv8YYFu8H1btvmrJy9FjjAWfb99wrhV3uhPFoNEr918utyR
echo "blabla" | ./target/release/subkey verify c4273e58b19b582330577f380041171d7aa9def2922e492e1b5510bc17a03f3fe19ae2b4f8089a7b4ba821fabffb97596245aa6caecf686a9ff119010374af8f 5Gv8YYFu8H1btvmrJy9FjjAWfb99wrhV3uhPFoNEr918utyR
And the result is ok:
Signature verifies correctly.