node hook_sumbit not working

Hi,

Recently i am working on a project where i found that when i create a page and submit for save, my drupal's (q=node/add/page) submit not working. I dig on this and i found that it (node_submit) is not called at all.

Then i create a seperate copy of the original drupal code and use the same database, its working there!

After dig more i found that the submit button code has changed to the following:

<input type="submit" name="edit[preview]" value="Preview"  class="form-submit" />
<input type="submit" name="edit[submit]" value="Submit"  class="form-submit" />

but in the original code is it is generated as follows:

<input type="submit" name="op" value="Preview"  class="form-submit" />
<input type="submit" name="op" value="Submit"  class="form-submit" />

I don't know where this things happens, or if the error is due to this.

Now how can i make workable my page node and where i make mistake ?
Can anyone help me ?

Shafiq