I keep getting the error on the last 2 lines, but not the cost line and i dont really get why, any help would be much appreciated.

`Sets

i POSITIONS / P1, P2, P3, B, DG, V1, V2, V3, H, F /

;

alias(i,j)

;

…

Variables

X(i,j) wether node i and node j are connected [binary variable]

C total cost of the connections

Binary variable X

;

Equations

cost, connected, self;

cost… C =e= SUM[(i,j), X(i,j)*sqrt(sqr(CX(i)-CX(j))+sqr(CY(i)-CY(j)))*VC+FC]

;

connected… SUM[(j), X(i,j)] + SUM[(j), X(j,i)] =g= 1;

self… X(i,i) =e= 0;

…`

Ive been whatver i can find online but from the examples i can find i cant really find the issue