Question: Failing to integrate a ODE

Hi all I have the following ODE

ODE_1:=diff(w(r),r)+R*(diff(w(r), r))^3=K/r;

ODE_T_1:=collect(algsubs(w(r)=u(r)+(r-1)*(U-0)/(delta-1), ODE_1),diff(u(r), r)) ;


 and when I try to do the following integration,

eq1:=int(phi[i](r)*ODE_T_1, assuming delta > 1;

it gives the following error


Error, (in assuming) when calling 'int'. Received: 'wrong number (or type) of arguments:
 for an operator integrand a range without a variable of integration is expected, 
got r = 1 .. delta'


Please help.

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