Failed to enable constraints

I have to admit I'm pretty new to ASP.net.

I'm trying to insert a row of data into my SQLExpress database table "Prets"

I'm getting the user_ID from the table "Membres"

Here's the code I have:

Imports System.Web.UI.Page
Imports System.Security.Principal
Imports WiseNetTableAdapters

PartialClass membre_sec_Pret_demande_pret
Inherits System.Web.UI.Page

Protected Sub submit_btn_Click(ByVal senderAs Object,ByVal eAs System.EventArgs)Handles submit_btn.Click
Dim UserAs String = My.User.Name
Dim pretAdapterAs New PretsTableAdapter
Dim membreAdapterAs New MembresTableAdapter
pretAdapter.AjouterPret(Convert.ToInt32(membreAdapter.GetUserIDbyName(User)), Convert.ToDecimal(montant_txt.Text), Convert.ToString(raison_txt.Text))
End Sub
End Class

And here's the error I get at runtime:

Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.

Description:An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details:System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.

Source Error:

Line 1610: }Line 1611: WiseNet.MembresDataTable dataTable = new WiseNet.MembresDataTable();Line 1612: this.Adapter.Fill(dataTable);Line 1613: return dataTable;Line 1614: }

Source File:c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\wisenetindustries\afc388c7\16067f12\App_Code.tyietv41.0.cs Line:1612

Stack Trace:

[ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.] System.Data.DataTable.EnableConstraints() +1820725 System.Data.DataTable.set_EnforceConstraints(Boolean value) +39 System.Data.DataTable.EndLoadData() +138 System.Data.Common.DataAdapter.FillFromReader(DataSet dataset, DataTable datatable, String srcTable, DataReaderContainer dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) +218 System.Data.Common.DataAdapter.Fill(DataTable[] dataTables, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) +318 System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) +221 System.Data.Common.DbDataAdapter.Fill(DataTable[] dataTables, Int32 startRecord, Int32 maxRecords, IDbCommand command, CommandBehavior behavior) +162 System.Data.Common.DbDataAdapter.Fill(DataTable dataTable) +107 WiseNetTableAdapters.MembresTableAdapter.GetUserIDbyName(String nom) in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\wisenetindustries\afc388c7\16067f12\App_Code.tyietv41.0.cs:1612 membre_sec_Pret_demande_pret.submit_btn_Click(Object sender, EventArgs e) in c:\inetpub\wwwroot\WiseNetIndustries\membre_sec\Pret\demande_pret.aspx.vb:12 System.Web.UI.WebControls.Button.OnClick(EventArgs e) +105 System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +107 System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +7 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +11 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +33 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5102

Make sure you have not insert duplicate values on the primary key column, you may take a look at this post:

http://forums.asp.net/thread/1213814.aspx

sql