crystal report runtime error 20599 Cannot Open SQL Server

I am using VB6.0 and crystal reports 8.5 the code which i have written is as below

sql = "{FinalWeeklydata.Shipmentdate} IN date(" & DT1.Year & "," & DT1.Month & "," & DT1.Day & ") TO date(" & DT2.Year & "," & DT2.Month & "," & DT2.Day & ") " & sql2
CrystalReport1.SelectionFormula = sql
CrystalReport1.ReportFileName = reportfilepath & "\rpt\ShipmentDetails.rpt"
CrystalReport1.Action = 1

i am getting an run-time error 20599 Cannot open SQl Server.

can anyone help me on this. as i am new to crystal reports i am unable to understand why this error is coming.

Thanks & reagrds,
Sharath.

have you connected the report to the database?

Please give the logon information during calling. Remove this forumla if u think this formula is creating problem and then run it.