Why does not nuke get the actual value?

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Greetings everyone and thanks ins advance

Well I am new to Nuke and recently a I did my first script, and something strange happens(at least for me). I use a for to print all the scale values of one transform node. My script is:

t=nuke.selectedNode()

for i in range(100):

scale=t['scale'].value()
print scale
nuke.activeViewer().frameControl(4)

or

for i in range(100):

nuke.frame(i)
scale=t['scale'].value()
print scale

The big problem is that it prints the same value 100 times, but I created 100 different key frames. so I really do not know what is going on.