HeyI have my traffic at FlyTampa's KBOS v2.1 showing below the elevation.my aircraft and other AI arriving land properly on the runway and taxi on the tarmac but the parked ones are showing up like this:I have tried re-installing it but it didn't help!Please Help! KBOS is my favourite airport!Thank you!

Does it happen at other airports too? Especially check any other airports in the area.If not and if then this problem is specific to KBOS, start with trying a different AFCAD file (there are some available in the AVSIM library).Just make sure the description/readme confirms it is for the addon scenery you are using (KBOS v2.1).Of course remember to deactivate the one you are using now (change the extension from BGL into BAK or just move it to a safelocation).Also check if you are not accidentally using two AFCADs at the same time (one of which could set wrong elevation). You can use ScanAFD for this purpose.

You also seem to have duplicate jetways (at least it looks that way on the screenshot). Any chance you have two copies of Boston installed for some strange reason? I'd go with Rafal's advice - check for duplicate AFCADs and failing that, if there are any other sceneries that could be interfering with Boston.