Applying for a Schengen visa for a second time; what documents should I attach? [duplicate]

I'm an Indian citizen and I am currently a third-year student in engineering. I have been selected to work for Google Summer of Code with VLC (VideoLAN) Organisation, which offered me an opportunity to visit their headquarters in Paris in June.

I did not have a passport, so quickly got one and applied for a Schengen visa. During the visa application process, I was asked the purpose of travel. I said attending a conference and tourism. When I got my biometrics receipt, it said my visa had been applied for under the business category. I was a bit surprised, but nothing could be done at that point. After a few days, my passport was returned with my visa refusal letter, stating the reason of refusal as "information provided is unreliable."

After I talked to my mentors at VLC, they agreed to let me try again and visit them in July. I will be applying shortly for my visa would like to know if there is anything else that I should include, apart from the usual documents.