I think the dart command doesn't work well if you choose the angle to be equal to 0º (that's parallel walls), you can choose any other angle but not zero.
I've seen the same problem in NX 8.5 and NX 6.0.
I don't think there is any workaround we can offer here. The message is pretty clear as to what the command expects for input. If you want it to work differently, your best option is to log an Incident Request (IR) or Enhancement Request (ER) with the developers (via GTAC): Help -> Online Technical support -> Log an incident with technical support.
If you COULD enter a value of 'zero' for the 'Angle(A)' and if it DID result in a 'Dart' feature, it would unfortunately NOT be manufactureable, at least not in the manner that one generally would manufacture something like that using a dia-set. Without at least some small angle, the material would never release from the die. I suspect that was the rational for NOT allowing the Angle to be set to 'zero' when this function was created. Now you can open an IR/ER if you wish, but I suspect that it will not get all that much consideration due to exactly what I've already mentioned.
John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
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Cypress, CA Siemens PLM: UG/NX Museum:
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