5/18/23: Looks like the recent TradeStation and/or Windows update broke (again) the TradeStation ELKIT interface which controls the TSL Next Open DLL.
So you will see a error message saying the TSLnextopen.dll is not working when you run a preprocessor or the general CEL testing shell.
Temporary solution: Until Windows and/or TradeStation repair the error, simply comment out the line of code in the EL Preprocessor that calls the TSLnextopen.dll. The theoretically perfect trading system will not be available, the perfect system arrows will not show up and you will not be able to use FF 34 or 35. This is not our first rodeo with Windows breaking the Next Open DLL. It is usually fixed in a subsequent update shortly.
We have a very simple patch update for this next open issue. Contact TSL for the update file.