Database log in dialogue pops up in clients machine

I have already posted this question under the tag SAP crystal report but not much help.

I have a report that is developed in windows 10 using Visual studio 2013 , Crystal report 13.0.17.2096 and SQL server 2012. Report is populated using dataset and it has one table. On development environment it works fine. This report is called from a menu item. Every day our client login to our main program then print this report many times in a day. When they print this report first time for the day, a database login dialogue box pops up and does not let them print report . They close this program and try it again and it works for rest of the day without any problem. Everyday client close our main program before they leave. This problem occurs everyday. Our clients use windows 10 and they have both 32 and 64 bit runtime. I also tried providing login info but did not work. All those reports are converted using Crystal report 13.0.17.2096 have same problem. Please help.

Here is my code:

'---these variables are defined at the beginning of the form

Dim sConnStr As String = _

"User ID=" & EntryPoint.ssUser & _

";Password=" & EntryPoint.ssPassword & _

";Initial Catalog=" & EntryPoint.ssDatabase & _

";Data Source=" & EntryPoint.ssServer

Dim mConn As New SqlConnection(sConnStr)

'---------------------------------------------------

'-----Code below is in button click event------------

Dim da As New SqlDataAdapter(sql, mConn)

Dim ds As New DataSet1

mConn.Open()

da.Fill(ds, "datatable1")

mConn.Close()

Dim objRpt As New SalesByContact '------report

objRpt.SetDataSource(ds.Tables("datatable1"))

CrystalReportViewer1.ReportSource = objRpt

CrystalReportViewer1.Refresh()