As our games are played by millions of people around all around the world play, it does mean that sometimes there can be a delay in messages reaching other players due to the sheer volume.
This is something we're constantly working to improve, however it does also rely on some factors which are outside our control, such as linked social media networks and internet providers.
If you're experiencing intermittent issues, what we would recommend you do is re-sending the request and if possible, check with your friend that they're receiving and responding to them.
However, if this does not solve your issue, please contact us and we will endeavor to address your issue.
It looks like you're new here. If you want to get involved, click one of these buttons!