r markdown message=false仍发出警告

我的r markdown块头如下:

```{r fluid_flowrate, echo=FALSE, message=FALSE, fig.height = 4, fig.width = 10}
# followed by my ggplot2 code
```

然而,我编织了HTML,得到了正确的情节,伴随着这个警告,打印了两次:

## Warning: Removed 1 rows containing missing values (geom_point).
## Warning: Removed 1 rows containing missing values (geom_point).

我想 message=FALSE 强制警告消失。为什么会出现?