why this error?Invalid attempt to read when no data is present

System.InvalidOperationException: Invalid attempt to read when no data is present. at System.Data.SqlClient.SqlDataReader.PrepareRecord(Int32 i) at System.Data.SqlClient.SqlDataReader.GetValue(Int32 i) at System.Data.SqlClient.SqlDataReader.get_Item(String name) at e_auction.temp.Page_Load(Object sender, EventArgs e)

I have check the query in QUERY ANALYZER, it worked pretty fine, but when i copy pasted, it is generating exception, I checked it, the part which is inbold is genearting exception and goes to catch part. i don't know y, help me plz

 Dim bool_bidUpdate As Boolean = True
 Dim lastBidder As Integer = 1
 Dim inc As Long = 5000
 Dim lastBid As Long = 175000
 Dim tempMax As Long = 0
 Dim tempBidder As Integer
 Dim tempBidDate As Date
 Dim tempCurrentBid As Long
 Dim myConnection As SqlConnection = New SqlConnection(ConfigurationSettings.AppSettings("ConnectionString"))
 Dim MydataReader As SqlDataReader
 Dim MyCommand As New SqlCommand()
 MyCommand = New SqlCommand("select * from temp1 where auctionId = 7 and maxBid > (select max(currBid) from temp1 where auctionId=7) order by maxBid DESC", myConnection)
 myConnection.Open()
 Try
 MydataReader = MyCommand.ExecuteReader()
If CInt(MydataReader.Item("uId")) = lastBidder Then
 bool_bidUpdate = False
 Else
 Do While MydataReader.Read()
 If tempMax < MydataReader("maxBid") Then
 If (MydataReader("maxBid") / (lastBid + inc)) >= 1 Then
 tempMax = MydataReader("maxBid")
 tempBidder = MydataReader("uId")
 tempBidDate = MydataReader("bidDate")
 tempCurrentBid = (lastBid + inc)
 End If
 ElseIf tempMax = MydataReader("maxBid") Then
 If tempBidDate > MydataReader("bidDate") Then
 tempBidDate = MydataReader("bidDate")
 tempMax = MydataReader("maxBid")
 tempBidder = MydataReader("uId")
 End If
 Else
 Exit Do
 End If
 Loop
 End If
 myConnection.Close()
 Catch b As Exception
 Response.Write(b.ToString)
 End Try
 If bool_bidUpdate = False Then
 Response.Write("no need to update")
 Else
 Response.Write("paleeeeez update" & " with uID: " & tempBidder & " with tempCurrentBid : " & tempCurrentBid)
 End If

You need to call reader's Read method at least once before trying to access its data.
then wat should i do, if i start it from the first if condition my whole logic ruins, coz reader only goes in forward direction, so wat shoud i do, one way ard could be i check if this loop is executing second time the first if condition shouldn't be executing but this is just hmm not a good approach?
wat do u suggest.

 'Read the first row
 If reader.Read() Then
 'Do the one-time check here
 'Continue normally in the loop
 Do
 'processing goes here
 '...
 Loop While reader.Read()
 Else
 'No records
 '...
 End If
 reader.Close()

Here is a way to check if there is a row/make a one time check and then continue normally.
it works fine as long as i don't use debugger, but whenever i inser any breakpoint, it gives me same error and goes to catch part. wat can be the prob
Where do you put breakpoints? What's the code you use now?
it generates error when it reaches to myDataReader part. i have put break point in various position sto check the prob, it still exists, wither its in some expression or either its some pace where i m using myDataReader. but when i run it without breakpoints it runs quite smooth.
i have changed the code to previous version, sorry for dat :)

 Try
 MydataReader = MyCommand.ExecuteReader()
 Do While MydataReader.Read
-->breakPoint iLoopcheck = iLoopcheck + 1
 If MydataReader.Item("uId") = lastBidder And iLoopcheck = 1 Then
 tempLastMaxBid = MydataReader.Item("maxBid")
 tempLastMaxBidder = MydataReader.Item("uId")
 bool_lastCheck = False
 Else
 newCurrentBid = lastBid + inc
-->exception Point If tempMax < MydataReader("maxBid") Then
 If (MydataReader("maxBid") / newCurrentBid) >= 1 Then