Express res.sendfile抛出禁止错误

我有以下代码：

res.sendfile( '../../temp/index.html' )

但是，它引发此错误：

Error: Forbidden
at SendStream.error (/Users/Oliver/Development/Personal/Reader/node_modules/express/node_modules/send/lib/send.js:145:16)
at SendStream.pipe (/Users/Oliver/Development/Personal/Reader/node_modules/express/node_modules/send/lib/send.js:307:39)
at ServerResponse.res.sendfile (/Users/Oliver/Development/Personal/Reader/node_modules/express/lib/response.js:339:8)
at exports.boot (/Users/Oliver/Development/Personal/Reader/server/config/routes.js:18:9)
at callbacks (/Users/Oliver/Development/Personal/Reader/node_modules/express/lib/router/index.js:161:37)
at param (/Users/Oliver/Development/Personal/Reader/node_modules/express/lib/router/index.js:135:11)
at pass (/Users/Oliver/Development/Personal/Reader/node_modules/express/lib/router/index.js:142:5)
at Router._dispatch (/Users/Oliver/Development/Personal/Reader/node_modules/express/lib/router/index.js:170:5)
at Object.router (/Users/Oliver/Development/Personal/Reader/node_modules/express/lib/router/index.js:33:10)
at next (/Users/Oliver/Development/Personal/Reader/node_modules/express/node_modules/connect/lib/proto.js:199:15)

谁能告诉我为什么会这样吗？