how to fixe error : Type mismatch : cannot convert from string to boolean in jaspersoft studio

[christmoney1]

I figure out Jaspersoft Studio and i'am trying to build a report. But when i click on "preview" to launch my report, i've this error:

" Type mismatch : cannot convert from string to boolean" then when i click on this error, jasper open my expression editor: "1.3. " + ($P{Langue_francais} ? "Date de naissance" : "Date, Place, Country of Birth")

/sites/default/files/user_uploads/christmoney1/capjasper.png

The parameter $P{Langue_francais} called in this expression is here:

/sites/default/files/user_uploads/christmoney1/capjasper1png.png

In this expression there is two another parameter $P{Langue_FR_EN} and $P{Campus_Berlin } which are enter by user when they launch report

There is someone who can help me with this.

Sincerely