Problems FirstIsland

I'm having problems with the Tutorial (http://www.opencroquet.org/index.php/Basic_Croquet-Cobalt_Island_Creator_Manual). I execute during some time the FirstIsland, but... some time after it... The Error:


doesNotUnderstand: aMessage
     "Handle the fact that there was an attempt to send the given message to the receiver but the receiver does not understand this message (typically sent from the machine when a message is sent to the receiver and no method is defined for that selector)."
    "Testing: (3 activeProcess)"

    (Preferences autoAccessors and: [self tryToDefineVariableAccess: aMessage])
        ifTrue: [^ aMessage sentTo: self].

    MessageNotUnderstood new
        message: aMessage;
        receiver: self;
        signal.
    ^ aMessage sentTo: self.

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fixTransformsIn: anActor
    "Traverse anActor and all its children checking for non-orthonormal transforms.
    Move these down until we get to the leaves and there transform the meshes (if any)."
    | tfm offset rowX rowY rowZ scaleX scaleY scaleZ scale |
    tfm := anActor localTransform copy.
    "Check if the transform is *really* weird"
    (tfm a41 = 0.0 and:[tfm a42 = 0.0 and:[tfm a43 = 0.0 and:[tfm a44 = 1.0]]]) ifFalse:[
        self error: 'Cannot fix transform'.
    ].

    "Remember offset of the transform"
    offset := tfm translation.
    tfm translation: 0@0@0.

    "Compute unit vectors to see if their length changes"
    rowX := tfm localPointToGlobal: 1@0@0.
    rowY := tfm localPointToGlobal: 0@1@0.
    rowZ := tfm localPointToGlobal: 0@0@1.

    "Normalize"
    scaleX := 1.0 / rowX length.    rowX *= scaleX.
    scaleY := 1.0 / rowY length.    rowY *= scaleY.
    scaleZ := 1.0 / rowZ length.    rowZ *= scaleZ.

    "Orthogonalize (later...)"
    (rowX dot: rowY) < 0.01 ifFalse:[self error: 'Not orthogonal'].
    (rowY dot: rowZ) < 0.01 ifFalse:[self error: 'Not orthogonal'].
    (rowZ dot: rowX) < 0.01 ifFalse:[self error: 'Not orthogonal'].

    "Create new orthonormal transform"
    tfm := Matrix4x4 identity.
    tfm a11: rowX x; a12: rowX y; a13: rowX z.
    tfm a21: rowY x; a22: rowY y; a23: rowY z.
    tfm a31: rowZ x; a32: rowZ y; a33: rowZ z.
    tfm translation: offset.
    anActor localTransform: tfm.

    "See if this a mesh"
    (anActor isKindOf: TMesh) ifTrue:[
        "Then rescale its vertices"
        scale := scaleX@scaleY@scaleZ negated.
        anActor vertices: (anActor vertices collect:[:vtx| vtx * scale]).
        anActor normals: (anActor normals collect:[:vtx| vtx x @ vtx y @ vtx z negated]).
        "And compute the bound spheres"
        anActor initBounds.
    ].

    "Scale children (using a matrix since we'll orthonormalize them later) and recurse"
    scale := Matrix4x4 withScale: scaleX@scaleY@scaleZ.
    anActor frameChildren ifNotNil:[
        anActor frameChildren do:[:child|
            child translation: child translation x negated@ child translation y @ child translation z negated.
            child localTransform: (scale composeWith: child localTransform).
            self fixTransformsIn: child.
        ].
    ].
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