Select return different values when executed outside function and inside a function

Hi guys,
By some reason my select return different result when I run it outside a function and inside a function.
This is what happens:

Ouside the Function
returns 3,89 (the comma is right, is exactly what I need.. here is exactly what I need)

Inside the Function
returns 3.89 (the dot replaces the comma)

and, if the result outside function is < than 1 like 0,03, it returns inside the function like .03

I'm geting crazy about this error, tried lots of ideas/solutions and I got nothing.

I'm running both selects with same user. and the function owner is the same user.

Any ideas?