i dont know what the problem is

[Zapheniah]

Sequence contains no matching element
at System.Linq.Enumerable.First[TSource](IEnumerable1 source, Func2 predicate)
at AA2Install.formMain.IsEnoughFreeSpace(String drivePath, Int64 requiredBytes)
at AA2Install.formMain.inject(Boolean createBackup, Boolean checkConflicts, Boolean suppressPopups)
at AA2Install.formMain.forceSelectedMods(Boolean suppressDialogs)
at System.Windows.Forms.ToolStripItem.RaiseEvent(Object key, EventArgs e)
at System.Windows.Forms.ToolStripMenuItem.OnClick(EventArgs e)
at System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e)
at System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e)
at System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea)
at System.Windows.Forms.ToolStripDropDown.OnMouseUp(MouseEventArgs mea)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ToolStrip.WndProc(Message& m)
at System.Windows.Forms.ToolStripDropDown.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)