network.Instantiate invalid cast error

hey can someone tell me what is wrong with this? funny thing is it works kind of half? it does instantiates over the network, but not as many as i would expect. also everything after the instantiate doesn’t work?
i get this error at the var clone: Transform =Network.Instantiate… line
error:
InvalidCastException: Cannot cast from source type to destination type.
creationSetup.makeOffspring () (at Assets/myAssets/scripts/creationSetup.js:86)

the things like repeat and some other are set by the player with some GUI sliders before the gameStart is true

function Update () {
	if (Time.timeScale == 1.0){
		var lifeTime: float= Mathf.SmoothStep(energy, 0.0, Time.time/speed);
		if (lifeTime == 0.0  repeat!= 0){
			this.renderer.enabled=false;
			networkView.RPC("makeOffspring",RPCMode.AllBuffered);
			repeat -=1;
		}
		if(CUBES){
		print ("cubes:"+repeat);
		}
		if(SPHERES){
		print ("spheres:"+repeat);
		}
	}
}
@RPC
function makeOffspring (){
	if(spawnScript.amITheSpheres){
		NetWorkGroep=0;
	}
	if(spawnScript.amITheCubes){
		NetWorkGroep=1;
	}
	if(startGame  networkView.isMine){
		
		for (var i: int = 0; i < offspring; i++){
			var grey: int= Random.Range(0, 128);
			randomPositions();
			var clone: Transform =Network.Instantiate (creature[i], randomPos, transform.rotation, NetWorkGroep);
			s -=0.01;
			clone.transform.localScale.x=s;
			clone.transform.localScale.y=s;
			clone.transform.localScale.z=s;
			clone.rigidbody.mass=s/2;
			clone.rigidbody.drag=s/2;
			if (red)clone.renderer.material.color=new Color32(Random.Range(120, 255), Random.Range(0, 60), Random.Range(0, 60),255);
			if (green)clone.renderer.material.color=new Color32(Random.Range(0, 128), Random.Range(50, 128), Random.Range(0, 50),255);
			if (blue)clone.renderer.material.color=new Color32(Random.Range(0, 50), Random.Range(0, 70), Random.Range(0, 255),255);
			if (yellow)clone.renderer.material.color=new Color32(Random.Range(180, 255), Random.Range(180, 255), Random.Range(0, 128),255);
			if (purple)clone.renderer.material.color=new Color32(Random.Range(50, 150), Random.Range(0, 50), Random.Range(80, 255),255);
			if (black)clone.renderer.material.color=new Color32(grey, grey, grey,255);
		}
		startGame=false;
	}
}

Network.Instantiate returns a GameObject type instead of a Transform type.

great!thanks Apples!!