Make sure you mIRC logs you as having joined, like this

[02:00] * jb_uk (jb_uk@jb_uk.tmi.twitch.tv) has joined #channel
[02:00] <@loz_bot> Hi jb_uk, *STREAMERNAME* is away, and will be back shortly.
[02:00] * jtv sets mode: +o jb_uk