Hi there....hopefully you are not still struggling with this, but here is the corrected version which should work...

Local cCheckName AS String

Scan
cCheckName = [.] + Alltrim(CheckBoxRules.Checkname)
With Thisform.Pages1._page1
? &cCheckName && evaluates to _Check1 of type object
cCheckName = cCheckName + ".AddProperty('cSqlString',&Rules)"
&cCheckName
Endwith
Endscan

I noticed you had a double period (..)....if this is necessary...modify the line accordingly.