REST - Token utilization

Hi.

In my API tests, while not using a browser, which asks authentication, I am trying to authenticate directly on my code. I am sending the follow POST request:

POST https://10.0.0.1/mgmt/shared/authn/login

{
"username": "admin",
"password": "myStrongPasswd",
"loginProviderName": "tmos"
}

I receive the token in the response, as follow:

"token": {
    "token": "MY_26_LENGTH_TOKEN",
    "name": "MY_26_LENGTH_TOKEN",
    "userName": "admin",
    "authProviderName": "tmos",

I can't see any errors in the response, so everything looks fine. After that, I try to send new requests using the token, as follow:

GET https://10.0.0.1/mgmt/tm/asm/signature-sets

{
"X-F5-Auth-Token": "MY_26_LENGTH_TOKEN"
}

But I receive as the response a message saying that I am not authenticated.

Authentication required!

    This server could not verify that you are authorized to access
    the URL "/mgmt/tm/asm/signature-sets".
    You either supplied the wrong credentials (e.g., bad password), or your
    browser doesn't understand how to supply the credentials required.

What I am doing wrong in this case?