The “Runtime Error 424 (Object Required)” error is caused by Excel being unable to access to an “object” referenced in your VBA code:
“Objects” are anything from a variable, file, worksheet, class or module.
The error is caused by a function being called on a reference you’ve either misspelled, or have not declared.
The solution is to ensure you have all the appropriate references declared within your code. The simplest ways to fix the problem is as follows:
Locate the offending line of code (if not highlighted, use debug mode)
Identify whether you’ve referenced any objects which aren’t declared
Look for any of the functions which may be causing an error and identify they are called correctly (with the correct syntax)
Remove as much code as possible in order to get the application working again, and then add back the lines one-by-one (this isolates the error and allows yo to fix any of the issues it may have)

I hope this is helpful!
Tim Paine