It sounds like you meant to post this in the Divine Divinity forum, rather than the Beyond Divinity forum (or read a description from DD and are trying to apply it to BD). In BD you right click on an item, and select Repair from the context menu.
For DD, after you click on the Repair skill icon to select it as your secondary skill, you need to right click on the ground somewhere to activate it (the cursor then changes to a hammer/anvil), and then left click on the equipment to be repaired (either equipped, in your inventory or on the ground).
It sounds like you got that figured out, though, so it is probably a case of insufficient Repair skill level. Level 1 will only repair up to 60% of the maximum durability, rounded down to the nearest integer. If the maximum durability of an item is 1, then you will need level 5 of Repair (100%) to fix it. Level 1 can repair up to 1 of 2, 4 of 8, 5 of 9, 6 of 10, 6 of 11, 7 of 12, etc.
In DD there is no way to increase the maximum durability. In BD you can use a charm to do this, but with Repair so easy and durability rarely an issue, this would be a waste of a charm slot IMO.
Welcome to the forum.
