Custom fields stopped workng

[ruisdb]

Hello. I had a custom field for the number of pages Ii own a bookstore).
Created with no problem, data introduced with no problem. It has no cart attribute: it's just an extra information for the customer.
I've used the integer data.
But recently (i cant't determibe exactly when) i can't any more introduce data.
In the products previouslt created i can see the custom field data and i can also edit it with success.
But if i create a new product i can't insert the custom field.
I go to "custom fields", i choose "number of pages" and nothing happens.
If i try to create another kind of custom field i have no problems creating it. But when i try to insert data nothing happens.
I am using joomla 2.5.17; vm 2.0.26a; php 5.3.28
In the data base, virtuemart_customs shows all the custom fields i've created, with the proper configurations
Can some one give me a clue of where to search for a solution?
Thanks.

[balai]

Check your browser's error console for possible errors when you are trying to add the CF

[ruisdb]

The problem was the plugin of the Button - Simple Image Gallery Pro.
I 've put if of and everythng seems ok.