For working with pages where you have to drag and drop something, you should use actions method.
// Instantiating an object of action class
Actions builder = new Actions(driver);
builder.keyDown(Keys.CONTROL)
   .click(someElement)
   .click(someOtherElement)
   .keyUp(Keys.CONTROL);
// Then get the action:
Action selectMultiple = builder.build();
// And execute it:
selectMultiple.perform();   
Or try implementing it with this code
Actions builder = new Actions(driver);
Action dragAndDrop = builder.clickAndHold(someElement)
   .moveToElement(otherElement)
   .release(otherElement)
   .build();
dragAndDrop.perform();
For more don't forget to check out this blog on how to drag and drop in Selenium?