Solved - Newly Created Elements Cannot Join Geometry in Revit API

Problem Scenario:
Implement the function of blocking walls between beams. After I create a wall, I hope to connect the upper beam with the wall to present a better visual effect, but when I directly use joinGeometry after creating the wall, an error will be reported indicating that connection is not possible.

Solution:
Regenerate the document.

Code:

using (Transaction trans = new Transaction(doc,"Create Close Wall"))
            {
                trans.Start();
                //Wall Type
                var duplicate = CreateWallType(doc,wallWidth, $"FBQ - {Math.Round(wallWidth * 304.8)}");
                var nWall = Wall.Create(doc, locationCurve, duplicate.Id, tLevel, value, 0, false, true);
                doc.Regenerate();
                if (!JoinGeometryUtils.AreElementsJoined(doc, beam1, nWall))
                {
                    //First join the beam and the wall. According to the cutting order, the wall will cut the beam. Next, switch the cutting order.
                    //Changing the order of the two components here will still be the wall cutting the beam.
                    JoinGeometryUtils.JoinGeometry(doc,nWall,beam1);
                    //Refresh document again
                    doc.Regenerate();
                    JoinGeometryUtils.SwitchJoinOrder(doc, beam1, nWall);
                }
                trans.Commit();
            }

Before Modification:


After Modification: