I used XNPV to verify that the NPV of the stream is not 0 using the return
given by XIRR.
I then tried to use Goal Seek (never used it before).

Given =XIRR(D3:D44, C3:C44), which returns -0.09833663106 in H2,
=XNPV(H2,D3:D44, C3:C44) returns -2820.37.

I then tried Goal Seek to determine the right value for H2, so I copied the
raw value to H11 and
used Goal Seek with =XNPV(H11,D3:D44, C3:C44) wich results in error
"Formula in cell must result in a number".

Goal Seek returns an error if the rate in H11 is negative.

Am I doing anything wrong?