CALCULATOR DNL/ INL DAC

Hi

I'm designing a 4 bit DAC.I have completed the schematic and The output waveform of the block is as follows

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I want measure INL error and I use INL function in calculator I try this expression

dnl(v("/net055" ?result "tran") 6.251e-5  ?mode "auto"  ?crossType "rising" ?delay 0.0 ?method "end" ?units "abs" ?nbsamples 16)

and it could't It does not work properly  the output waveform is as follows

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Where is the problem? 

 is my method to use this function currect ?

THANKS

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