Question: weird error that I don't understand

Hi in trying to solve these coupled differential equations i get a weird error:

> t := diff(X(x), x) = -(1-6*R(x)^(1/2))^(1/2)*x*X(x)/(X(x)*x+R(x))^(1/2), diff(R(x), x) = (1-6*R(x)^(1/2))^(1/2)*x^2*X(x)/(X(x)*x+R(x))^(1/2);
                                        (1/2)         
                       /          (1/2)\              
           d           \1 - 6 R(x)     /      x X(x)  
          --- X(x) = - -----------------------------, 
           dx                             (1/2)       
                           (X(x) x + R(x))            

                                        (1/2)        
                       /          (1/2)\       2     
             d         \1 - 6 R(x)     /      x  X(x)
            --- R(x) = ------------------------------
             dx                            (1/2)     
                            (X(x) x + R(x))          
> init(R(0) = 0, X(0) = 100);
                   init(R(0) = 0, X(0) = 100)
> Solve({t, init});
Error, (in PDEtools:-casesplit) the input system cannot contain equations in the arbitrary parameters alone; found equation: init

I am using PDE tools, please can someone help.