Android: If Map contains Value, Change Button Resource Not Working
===

I have a favourites button and I want it to change it's image depending on whether an ID is found in a favourites map, however it doesn't seem to be working.
Here is my code:

    boolean containsVenue = false;
    			 for (Map<String, String> hashMap : TabsViewPagerFragmentActivity.favouritesData)
    		        {
    		            
    				    containsShop = hashMap.containsValue(shopID);
    				    
    		        	
    		        	
    		        }
    			 
    			 if(containsVenue) {
    				 isFavourite = true;
    				 favouritesBtn.setBackgroundResource(R.drawable.is_a_favourite);
    			 }  else {
    				 
    				 isFavourite = false;
    				 favouritesBtn.setBackgroundResource(R.drawable.favourite_normal);
    			 }
			 
It seems to set the button to "R.drawable.favourite_normal" even if the ID is in the map.
What am I doing wrong?