When I opened an application on SERVER it working fine but when I tried to open it with ACCESSPOINT it gives me some null values.
Section access is applied.
I am using QV11.2 SR5
Then it is possible that data reduction is causing some expressions to return null values.
You may be opening it with ADMIN access when you open it on the server - I assume that you are using QV desktop on the server?
When you open in the access point, you are opening in USER mode, regardless of your access level in the section access script.
It will happen if you use Section Access because of Data Reduction. May be you logged as Admin in server where as you logged in as User in Access Point so that you are getting these Null Values.