Fail Build from VBScript

[modernrocketry]

I am using the tlbimp command in a build and have noticed that when an error occurs, the build continues.

So I cobbled together a vb script to parse the LASTSTEP_OUTPUT and look for an error (TlbImp : error)
Everything works as planned, except stopping the build if an error is found.

I thought "Step.BuildStatus = vbldStepStatFailed" would stop the set, but it reports succeeded and keeps going.
What am I doing wrong?

output = Split(Application.Macros(vbldMacroSystem)("LASTSTEP_OUTPUT"), vbCrLf)
For i = 0 To UBound(output)
    strSearchThis = output(i)
    if instr(strSearchThis, "TlbImp : error") > 0 then
         Builder.LogMessage "TLB ERROR FOUND"
         Step.BuildStatus = vbldStepStatFailed
         Exit for
    end if
    
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