在创建数据库一步出现下列错误，不知原因在那？请帮帮我。

Server Error in '/' Application.

Length cannot be less than zero.
Parameter name: length

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.ArgumentOutOfRangeException: Length cannot be less than zero.
Parameter name: length

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[ArgumentOutOfRangeException: Length cannot be less than zero.
Parameter name: length]
   System.String.InternalSubStringWithChecks(Int32 startIndex, Int32 length, Boolean fAlwaysCopy) +9389291
   System.String.Substring(Int32 startIndex, Int32 length) +11
   Kesion.Publics.Utils.CutHttpString(String str, String start, String last, Int32 n) +1009
   Kesion.Publics.Utils.CutHttpString(String conStr, String startStr, String overStr, Boolean includekeytag) +110
   Kesion.ICMS.InstallIndex.NSHgZEBcpk(String , String ) +101
   Kesion.ICMS.InstallIndex.BtnStep2Next_Click(Object sender, EventArgs e) +151
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +118
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +112
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1