advice Offer Accepted No Response

Please how can i handle this, i received 3 offers on one of my domains on DAN platform
1. $100
2 $1000
3 $1000
I rejected the $100 offer, while i accepted the $1000 offer. Few minute after accepting the $1000 offer i had another $1000 offer, Since i had accepted the first offer i refuse to act on the second $1000 offer, i leave it open, but the person who made the first offer refuse to make payment, though DAN had send reminder to him, after 5 day i was suspecting he might not fulfill his commitment.

I now open up discussion with the second person who made another $1000 offer buy posting counter offer of $2500 my intention for this is to open up conversation.
After seven day the first person i accepted his offer refuse to make payment and DAN cancel the transaction.
Then opened up conversation with the person who offered me $100 that i rejected, by giving him $1500 counter offer to open up conversation. Non of them has responded.

What have i done wrong ?
What is the right way i should have responded ?
What advise can you give me now.
Thanks
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