how is status of a KPI like non-compliant or non-compliance decided?

hi,

i have inserted a timer on my form and timer failure field is set as Resolve by field of applicable SLA.

i have also set warning condition on resolve by status (nearing non-compliance), now i want the timer to turn orange like in normal cases, but it doesn't seem to work. how is nearing non-compliance condition applied internally for a KPI, can anybody explain?please!!!