share section diameter

[serafina]

Good morning to all
I have searched in the forum but I can't do it: I'm probably too prevented.
I would like from a view in the section to place the share of a diameter by selecting an axis (or a half-way line) and another point of geometry. igo image . I have sw 2017, I found in forum where they say to point on the axis and the geometry chosen, but to me it does not work, it only puts the quota "80" if nza possibility i turn it into diameter.
thanks in advance

 

[MassiVonWeizen]

because that type of quotation only works in the sketches in part environment.
in the design environment you have to quote the ends of the diameter or in case you insert a line of construction from sketch after having put the quota go in the board Association lines and choose the diameter item or right button on the quota and choose creates an iametric quota