slidify embeds plotly plots as images rather than as normal interactive plots

[enrico200165]

I am trying to include some plots built using plotly in slides generated from .Rmd using slidify.
The problem is that the plots are rendered as images instead of being interactive.
On the same .Rmd file if instead of using slidify to produce html slides I use knitr to produce an ordinary html pages the plotly plots are interactive.

To produce and display the slides (with plot images instead of desired normal itneractive plot) I am using slidify with the following commands:
slidify("a.Rmd"); browseURL("b.html")

To produce and disaply the normal html page (that correctly shows the interactive plotly plots) I am using:
rmarkdown::render("a.Rmd"); browseURL("a.html")

PS. before posting the issue also posted the question to stack overflow
http://stackoverflow.com/questions/43111083/slidify-embeds-plotly-plots-as-images-rather-than-as-normal-interactive-plots