分析tweet时的streamR字符问题

当我使用此代码并开始从我的帐户捕获tweet时，没有找到该tweet。只有在使用İ、Ö、Ü、Ğ字符时，才会发生此错误。ı更改了编码设置，但不工作。你能做什么

file = "tweets.json"
track = "kikik,kükükü,üğüğü"
lang = "tr"
minutes = 0.5
time = 60*minutes
filterStream(file.name = file, 
             track = track,
             language = lang,
             timeout = time, 
             oauth = my_oauth)