how to make a program to filter (lowpass) the waveform from my initial waveform

[Dennis_Knutson]

I removed the read file function since you did not attach a file to be read and then ran the VI. No errors occurred with the default values of the controls. Everything seems to be working just fine.

[sabaukusauso]

here i attached the error appeared.

[KateB]

Just make sure that you configure express vi to match with condition mentioned in error screenshot, and error will not occur again.

[sabaukusauso]

hthis is the problem error.

[Dennis_Knutson]

Posting the error message again does not do any good. As already mentioned, the VI that you posted does not have any errors when run. You must be changing something before you run it and not saving it. What is the actual frequency you set when you run it and what do you set the filter to. It sounds like you have set some illegal filter parameters.