If the property has an offer that doesn't necessarily mean the offer's been accepted. If the offer has been accepted by the seller and both the buyer and seller have signed the purchase agreement/offer, then it is a legally binding contract. Once the contract is binding, the listing agent needs to change the status in the MLS to either Backup or Pending. They don't remove it from the market until Escrow has closed and Title to the property has transfered. Then the status in the MLS is changed to Sold.
If your agent has questions and the listing agent will not return their calls, have your agent call the listing agent's Broker.