error - string is required

Hi

This is the string

str = "select transactionno,tdate,tarewt,taredt,taretime,grosswt,grossdt,grosstime,netwt,grossshiftdate,tareshiftd ate,grossusercode,tareshiftcode,grossshiftcode from transact,customer,product,users where grossshiftdate='" & (Format(DTPicker1.Value, "MM/dd/yyyy")) & "' union select transactionno,tdate,tarewt,taredt,taretime,grosswt,grossdt,grosstime,netwt,grossshiftdate,tareshiftd ate,grossusercode,tareshiftcode,grossshiftcode from transact,customer,product,users where tareshiftdate='" & (Format(DTPicker1.Value, "MM/dd/yyyy")) & "'"

Report.ParameterFields(1).SetCurrentValue DTPicker1.Value

dtpicker1.value is 03/15/2014 9:14:17 PM , Grossshiftdate in Database is 2014-03-15 , tareshiftdate is null

I am using Sql Server 2008 R2

Thanks