I am trying to do the following:

SetVariable[ $a, field_name ]

...

PerformFind[ Restore ]

Under the find step, I specify find requests, and try to set the criteria to equal the variable, by entering "$a" as the criteria.

This doesn't work. Why? Is there something else I can specify here? I worked around it by doing:

[Enter Find Mode]

[set Field]

[Perform Find]

But that is a little lame because I have to have the field on the layout that I am on.

So, what's going on here? Is this not an option? A known issue?

Thanks for the help.

No, you can't restore a variable value.

Use the other method:

Enter Find Mode[]

Set Field [ field ; $a ]

Perform Find[]

...

And Set Field[] does NOT require the field to be on the layout.