[Axiom-developer] Am I posing this solve problem wrong?

[C Y]

I'm trying to solve for y.  In Axiom:

(1) -> E1 := x^2*D1^2+(y-y1)^2*C1^2 - C1^2*D1^2
(1) -> 
          2  2      2         2 2     2 2     2  2
   (1)  C1 y1  - 2C1 y y1 + C1 y  + D1 x  - C1 D1
                                                     Type: Polynomial
Integer
(2) -> solve(E1=0,y)                           
(2) -> 
           2  2      2         2 2     2 2     2  2
   (2)  [C1 y1  - 2C1 y y1 + C1 y  + D1 x  - C1 D1 = 0]
                              Type: List Equation Fraction Polynomial
Integer

Am I doing something wrong?  Maxima doesn't seem to have a problem:

(%i2) E1 : x^2*D1^2+(y-y1)^2*C1^2 - C1^2*D1^2;
                          2   2    2   2           2   2
(%o2)                 - C1  D1  + x  D1  + (y - y1)  C1
(%i3) solve(E1 = 0, y);
                     2    2                         2    2
              sqrt(C1  - x ) D1 - y1 C1      sqrt(C1  - x ) D1 + y1 C1
(%o3)  [y = - -------------------------, z = -------------------------]
                         C1                             C1



      
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