SaveAs method throws exception

I'm working on a .NET program to interface with Excel. The code looks like this:

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As you can see, it is simply used to convert an .xlsx file to a .xls file (Excel 97-2003 format).

When I run this code it throws exception:

System.Runtime.InteropServices.COMException was unhandled
HResult=-2146827284
Message=Exception from HRESULT: 0x800A03EC
Source=testcs
ErrorCode=-2146827284
StackTrace:
at Microsoft.Office.Interop.Excel._Workbook.SaveAs(Object Filename, Object FileFormat, Object Password, Object WriteResPassword, Object ReadOnlyRecommended, Object CreateBackup, XlSaveAsAccessMode AccessMode, Object ConflictResolution, Object AddToMru, Object TextCodepage, Object TextVisualLayout, Object Local)
at testcs.Program.ConvertToXls(String xlsxFn, String xlsFn) in c:\Users\Redirection\brittg2\Documents\Visual Studio 2012\Projects\testcs\Program.cs:line 104
at testcs.Program.Main(String[] args) in c:\Users\Redirection\brittg2\Documents\Visual Studio 2012\Projects\testcs\Program.cs:line 95
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.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException:

While troubleshooting, I ran the steps in my code interactively in Excel. They worked as expected and the converted file appeared in the destination directory.

I should mention that the destination directory is on a different computer. The second argument to the function is given as a UNC path.

Any ideas what's going on here?

Found the answer:

xlExcel9795 is deprecated, though still in the enumeration. If you use it, an exception is thrown.

See: https://social.msdn.microsoft.com/Fo...forum=exceldev