I can't understand why this code is wrong, the error message is: 

```
error: '}' expected but '.' found.

```

on line

```
this.tX = cX

```

code:

```
class Quaternion {  
  private var tX: Float = 0
  private var tY: Float = 0
  private var tZ: Float = 0
  private var tW: Float = 1

  def this(cX: Float, cY: Float, cZ: Float, cW: Float) {
    this.tX = cX
    this.tY = cY
    this.tZ = cZ
    this.tW = cW
  }

  ...

```

Please help me fix my probably obvious mistake.