When the AutoLength property of the specified callout is set to False, the Length property returns the length (in points) of the first segment of the callout line (the segment attached to the text callout box). Applies only to callouts whose lines consist of more than one segment (types msoCalloutThree and msoCalloutFour). Read-only Single.
Remarks
This property is read-only. Use the CustomLength method to set the value of this property for the CalloutFormat object.