sometimes the relationship between tge real exchange rate and the trade balance of a country may nit comply with the theory as

i) trade balance depends on factors other than the real exchange rate

ii) real exchange rate does not move as much as the trade balance does

iii) even when a countrys currency depreciates because of the trade barriers the other countries cannot import much from the country

iv) sometimes exports and imports are not priced in local currencies so quantities of exports ans imports do not change when the local currencies appreciate or depreciate