Hi welcome to our forum.
Your post has not enough information for anyone to help.
1 Is the universal remote a humax supplied device. ?
2 If yes what Humax BOX was the Box supplied with ?
3 If it’s a Humax remote and you remove the batteries and look carefully what is the device code.
There has been different remotes supplied some of which had 3 or4 digit codes to control other kit. The manual you had with the box should have had the codes included.
If a non Humax remote consult the website of the remote control supplier.