Okay so i tried 3 times to compound a Silver Armor with 2 iron net boots and 1 demon gloves, and every time i got 'sharper sword'
why?

Iron Net Boots+Demon Gloves - for primary alch skill
Iron Net Boots+Demon Gloves+Iron Net Boots - for Junior alchemy skill

and... u have to try many more times. 3 is to less, try 50 :)

u need a lot of money if u wanna try to compound a weapon

primary alchemy says 2 iron net bootssomeone should change that
cause im doing this on my alt >.<"

Check main website forum. In order to get a better chance of compounding higher level items, you need a higher level of primary alchemy. For this item, I think even a higher level junior is highly recommended.

But yes, the recipe for primary DOES work, it just wastes an extra item. XD

The recipe isn't invalid, it just isn't efficient. This is partly because many of the recipes entered originally did not have the <Alchemy Field> filled in appropriately. If you don't understand why the recipe works, I recommend doing a little more research before potentially burning through alot more gold.

Synthesis Paradise has alot of guides like this, anything by TheRealRafoi is highly recommended.

If the problem is that you don't have a sufficient level alchemy, the high recommendation by those who don't mind being clickish is make small wooden gears from lauan wood (via manufacturing) and after you make a few stacks of that, start compounding them with each other. You will eventually get a couple of lauan wood back or other wood items which can be recompounded again and again. Since there is no manufacturing time, you can actually come out ON TOP in terms of wood if you are lucky enough. The other side of that is of course that each compound click gets you closer to the next level of alchemy.

Yeah, keyoshikira get it right. It is a +3 rank for junior, not very common for primary/junior, need some luck ^_^. Just depends who post the formula, it work with primary too, but ofcoz .. wasted.

hmm that weird just today i used same thing as u and got 3 in a row funny how alchemy works i used primary and it at a 7 so all i can say is keep tring ull get it eventually