F1 car front & Back Delta Help

In F1 2019/2020 I cannot seem to get the correct car in front or behind delta. Often the delta will be off by quite a few seconds and for example if a back marker car gets in the way etc it then shows the delta to that car instead of the car you are racing. 

Here is the script I use for driver ahead for example (taken from another dash) its probably not correct.

if(isnull([PersistantTrackerPlugin.DriverAhead_00_Name],'')='','',format( isnull([PersistantTrackerPlugin.DriverAhead_00_Gap],'0'),'0.000'))

Is there anyone who can provide me with the correct car in front delta  and car behind delta script that shows the actual cars you are racing front & back as a delta time

Its driving me crazy