Unhandled Error when downloading new prices

[bradleybauer]

Open app -> open "Update Prices" tab -> check "Molecular-Forged Materials" -> click "Download Prices" -> app crashes almost immediately.

An Unhandled Exception has occured and EVE Isk per Hour will now close.

Please fill out the following information so I can reproduce the bug

What is your Operating System?
What tab or screen did the error occur?
What are the steps to reproduce the Error?
Web link to a screenshot of your error:
In addition to a screenshot, copy the data below and send to developer.

Source: Microsoft.VisualBasic
Message: Conversion from string "" to type 'Long' is not valid.
Raw Error Text: System.InvalidCastException: Conversion from string "" to type 'Long' is not valid. ---> System.FormatException: Input string was not in a correct format.
at Microsoft.VisualBasic.CompilerServices.Conversions.ParseDecimal(String Value, NumberFormatInfo NumberFormat)
at Microsoft.VisualBasic.CompilerServices.Conversions.ToLong(String Value)
--- End of inner exception stack trace ---
at Microsoft.VisualBasic.CompilerServices.Conversions.ToLong(String Value)
at EVE_Isk_per_Hour.MarketPriceInterface.UpdateESIMarketOrders(List1 CacheItems) at EVE_Isk_per_Hour.frmMain.LoadPrices(List1 SentItems)
at EVE_Isk_per_Hour.frmMain.btnImportPrices_Click(Object sender, EventArgs e)
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
Error Tracking: