-nan problem???

[Sheridan]

Hi!

I am new in D language. I implement a little 2D/3D engine, and during the 
development I faced an interesting problem.

I have this function:

 void addBackgroundToLayer2(char[] textureName, float posx, float posy)
    {
        CTexture tex = new CTexture(textureName); //create the texture

        tex.m_itexurePosX = posx;
        tex.m_itexurePosY = posy;
       
        writefln("X: %f, Y: %f", tex.m_itexurePosX,tex.m_itexurePosY);

        m_Layer2~=tex;
    }

The problem is that the value of tex.m_itexurePosX variable will be "-nan". But 
value of posx is good.

If I change the sort of the lines:

 void addBackgroundToLayer2(char[] textureName, float posx, float posy)
    {
        CTexture tex = new CTexture(textureName);

        m_Layer2~=tex;

        tex.m_itexurePosX = posx;
        tex.m_itexurePosY = posy;
       
        writefln("X: %f, Y: %f", tex.m_itexurePosX,tex.m_itexurePosY);
    }

Then everything works fine. What do I wrong? I do not understand this problem. 
I use dmd 1.037 compiler.