Set field has two specify buttons and you must use both.
Click the first specify button to select the field shown to the left of the semi-colon. Click the second specify to enter the expression to the right of it. Do not enter the semicolon, filemaker will add that for you.
What type of field is FollowUpdate, date or number? (It should not be text). I've give two versions of the Set Field step below depending on your field type.
Your script should look like this when you are done:
Enter Find Mode  //clear the pause option
Set Field [ IssueTable::FollowUpdate ; "<" & Get (CurrentDate) ] // If followUpdate is a date field
Set Field [IssueTable::FollowUpdate ; "<" & Day ( Get (CurrentDate) ) ] //If followUpdate is a number field (date is likely your best option here).
Set Error Capture [on] //Supresses the "no records" dialog if there are none to find
Perform Find 
Sort Records [Restore; No Dialog]
It's almost the end of my week, so if I read your post incorrectly, I apologize.
It sounds as though you want to user to go to a report that shows all tasks that require a followup if the followup date has passed or is today.
Assuming you want it to run when the user goes to the layout
All User Abort [off]
Set Error Capture [on]
Enter Find Mode [ ]
Set Field [issueTable::FollowUpdate; " ≤ "&get(currentdate)]
PerformFind [ ]
show custom dialogue ("There are no tasks require a followup at this time")
Thank you so much for your quick reply. When I attempted to add your code, I got the same error code I mentioned before. I don't understand why it is asking for a operator here. Please take a look. It looks like it is expecting the result to be text...not a date or a number. However, my field is absolutely a date field. See error below:
Appears you have your field set as text and it should be set as a date. Go to manage-database-fields and change the field type to date.
See the first part of my post. IssueTable::FollowUpdate should not be in this dialog at all.
Thank you so much for your response, lloyddd. Can you take a look at the error code I'm getting? I've been getting it all day. I put an image on my last post...
I'm confused looking at your image. You don't set the field name in the calcuation. That is a differnet parameter. You calculation should look as follows:
" ≤ "&Get(CurrentDate)
And the field should be set in the "set field" parmater of the "set field" script step. It is usually in the lower right hand screen of the script editor.
Sigh... That's what I've been trying to point out now for several posts...:smileysad:
Yes sir. I now understand what you mean about using the two buttons and how Filemaker compiles the input from both of them into one script line. It works perfectly. Thank you so much, Phil. I really appreciate your help.
lloyddd, thank you so much for your replies. I got it working. You guys really helped me out today.
What about the other issues I pointed out in my first post? The data type of your field IS important--it just wasn't the cause of the error message you were getting.