VLA-ADDSPLINE help

I am creating a lisp that draws splines using Vlisp.

Below is the current code I have it doesn’t quite work the way I want it to.

Points 3 (P3) and Points4 (p4) should be end and start tangency according to the addspline function.

 [/font]
[font=Tahoma](SETQ P1 (GETPOINT "\nSpecify Start point"))
(SETQ P2 (GETPOINT P1 "\nSpecify End point"))
(SETQ P3 (GETPOINT P1 "\nSpecify Start Tangency point"))
(SETQ P4 (GETPOINT P2 "\nSpecify End Tangency point"))[/font]
[font=Tahoma](setq spc (vlax-get-property (vla-get-ActiveDocument (vlax-get-acad-object))
    (if (= 1 (getvar 'CVPORT))
      'PaperSpace
      'ModelSpace)))[/font]
[font=Tahoma](setq mld (vlax-invoke spc 'addspline (append p1 p2) p3 p4))[/font]
[font=Tahoma]

Does anyone know a shorter or more efficient way to draw to a spline using dxf or visual lisp, any additional information on each way would be useful.

Regards,

CadWarrior