The seller could have multiple offers to buy and is working with the most likely to purchase. See if the item is taken off the market or marked as sold within a week or so.
Out of courtesy they should at least respond.
Seller Silence
On two occasions during the past month I have posted a question to a seller about whether the item still has a manufacturers warranty. One selling an Aurender N20 and the other a JVC NZ700 projector. Neither has responded even though it has been a few weeks.
There should be a way to leave seller feedback before a sale to inform potential buyers of this issue.