In order for something to operate correctly ("Transformer" for your LED light in this instance) it requires a supply consisting of live and neutral (also earth for safety) At most switches you only have Live and Switched live. (With 2 way switching you have live, switched live and "common" as it is common to both switches) As you said you have tried every combination with no success, the reason is you have no neutral at the switch. Since you are inexperienced I would suggest you fit a plug to your transformer and plug it in, it will be safer and should cause no problems.
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