在点赞时进行字符串拼接时，拼接图片时报错

![qq 20161012182123](https://cloud.githubusercontent.com/assets/14331075/19306538/bfe5b600-90a8-11e6-8ead-aaf6fce9f619.png)
为什么我这样写会报错
![qq 20161012182342](https://cloud.githubusercontent.com/assets/14331075/19306602/0d4c7c30-90a9-11e6-8c2c-ae96bda2afbe.png)
![qq 20161012182351](https://cloud.githubusercontent.com/assets/14331075/19306611/14db59ee-90a9-11e6-9136-d00a307ba877.png)

提示这个地方报错，这个怎么弄
