Using Microsoft reportviewer in VB.Net a textbox does not show a integer.

I have a textbox in the report header with the following expression :

Code:
= "Verkope (k" & CHRW(8467) & ") : "   & first(Fields!Finjaar.Value, "DataSet1") & " finansiële jaar"

The report runs without errors but the part

Code:
first(Fields!Finjaar.Value, "DataSet1")
does not show.

Finjaar has a Integer value in my MySQl database. If I use any other text value instead of Finjaar the expression executes correctly. Clearly an issue with Integer values. But I just cannot figure that out.

Any help would be great.