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Thank u for the reply.I have a question please kindly answer that. So if the 4th seater replies 2nt against 1st seater's opening call without any interference it shows 19-21 balance hands not unusual 2nt but if 4 seater calls 2nt after 1st seater and his partner call 1♠,2♠ respectively. would that show unusual?

My LHO made an opening call 1♠,My partner & MY rho called pass & I replied with 2nt with Aqjxx in ♦& ATxxx in ♣. I had 13 hcps. Without any interference by opponents our call went out like 3♦-4♦-5clubs-5♦. But when I saw my partner's hand he had void in ♦.As per his profile He is an expert.So could someone please tell me what went wrong? And if possible please tell me elaborately the response procedure of unusual 2nt. p.s.-I put an alert on my 2nt as in minors with same length.