A formula for IRR

[salvomic]

why this code gives -1?
(the formula from akmon is ok in Home (not in CAS)...
<< fsolve(ΣLIST(MAKELIST((L1(I)/X^(I-1)),I,1,SIZE(L1))),X)-1 >>

Code:


EXPORT IRR(flows)
BEGIN
local I, irr, sz;
sz:= SIZE(flows);
irr:= fsolve(ΣLIST(MAKELIST((flows(I)/X^(I-1)),I,1,sz)), X)-1;
RETURN irr;
END;