Visual Basic 2010 Error Any Help? :3

System.InvalidCastException was unhandled
Message=Conversion from string "" to type 'Double' is not valid.
Source=Microsoft.VisualBasic
StackTrace:
at Microsoft.VisualBasic.CompilerServices.Conversions.ToDouble(String Value, NumberFormatInfo NumberFormat)
at Microsoft.VisualBasic.CompilerServices.Conversions.ToDouble(String Value)
at Advanced_Spammer.Form1.Timer1_Tick(Object sender, EventArgs e) in C:\Users\Blue\documents\visual studio 2010\Projects\Advanced Spammer\Advanced Spammer\Form1.vbine 5
at System.Windows.Forms.Timer.OnTick(EventArgs e)
at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
at Advanced_Spammer.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vbine 81
at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException: System.FormatException
Message=Input string was not in a correct format.
Source=Microsoft.VisualBasic
StackTrace:
at Microsoft.VisualBasic.CompilerServices.Conversions.ParseDouble(String Value, NumberFormatInfo NumberFormat)
at Microsoft.VisualBasic.CompilerServices.Conversions.ToDouble(String Value, NumberFormatInfo NumberFormat)
InnerException:
-------------------

It says invalid Exception was unhandled


Edit - This is the code

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Timer1.Interval = TextBox3.Text
SendKeys.Send(TextBox1.Text)
SendKeys.Send(TextBox2.Text)
SendKeys.Send("{Enter}")

I'm guessing that Timer1.Interval takes a Double, but it can't convert the contents of TextBox3.Text to that type. As a test, try putting a number in the line you assign a value for Timer1.Interval. If it doesn't give you the error, you must find out why it can't convert the text to a double (probably you don't have a number in the text?).

Le not a programming tutorial.
Le moved.