There's not quite enough info for us to help.
"I encounter a debug"..
Ok... what is the code, and when you get the "debug", what is the error, and
what line is it stopping on?

if you want it to run  every 1/2 your, you can set up a scheduled task to open
the excel  file.
But keep in mind that it will tie up your Excel session every 1/2 hour, so you
may want to run it on a
machine that isn't being used by a user.

or... you said you want to "paste it into excel".
Is the Excel file just a collection of data? Is the data  being pasted to the
end of a list of data?
If so, perhaps you can just append the data to a comma separated file that can
be used by Excel.

The process  involves copy  the data  from a database (a server  in a company) and
the paste  the same into excelsheet. This process is it to repeated after half an
hour as trades get append on the database.

Now the error here is that a recorded a macro  for the process but when I run  the
macro it debug  saying "ActiveSheet.Paste". Do u want the entire coding?

If the database Server is SQL Server, then you can set up a DTS package to
run every 30 mins.
The DTS package will just run  every 30 mins, and copies over the data  into
an excel  file.
I hope this helps.

Is what you described: "ActiveSheet. Paste" accurate?
If it is, then the problem  is with the "space" before the "Paste"
It should read "ActiveSheet.Paste". (no spaces)

Now, to carry your question further:
Is it your intent to have the excel  file Opened every 1/2 hour to do this
update?
If so, as I mentioned in my previous response, it will be VERY distracting for
any
user sitting at the computer where this job is running.
My earlier comments were inquiring whether having a VBScript job run  every 1/2
hour and update a .dat file. Then, when a user launches your application, it
would
go out and retrieve the latest data  from the file.
this would work, unless you're doing quite a bit more than just copy/pasting
data
into an Excel file.

I guess I shouldn't try to re-engineer your process, and just help by answering
the question
asked.

so.. if the above mentioned "space" is not the problem, I'll need more of the
code and the
exact wording of the error to be able to address your problem.