can not set cascading property while single property set works

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C#

VS2012

Following Code does not set the property.
It just does nothing and at debugging just jumps ahead, even with F11

job.TDataReference.CheckedOut = false;

job is of Type TJob
A class I build myself with the property:

public TDataReference TDataReference
{
    get
    {
        return new TDataReference(this.DataReference);
    }
    set { this.tDataReference = value; }
}

TDataReference is also a class I build myself with the property:

public bool CheckedOut
{
    get { return (dataRow[CHECKEDOUT].ToString() == "True"); }
    set { dataRow[CHECKEDOUT] = value.ToString(); }
}

and and the private member dataRow of Type DataRow

What is funny is that following code works fine and sets the property:

TDataReference dr = job.TDataReference;
dr.CheckedOut = false;

Who can explain that to me.