Setting values from iframe(aspx page ) to incident form

Hi,

I'm using Dynamics crm 2015 (db 7.0.2.53) i migrated from crm 4.0. now i'm integrating into crm 2015 some customizations which already exist into crm 4.0.

So i created an iframe(aspx page) in the incident(case) form, this iframe must to display a textbox and a button. i have to insert a text to seach and i click on the button to find the contract informations. Normally the search results on the iframe (aspx page)contain an action to update informations on the incident form directly.

I displayed the iframe on the form without problem but now i can't access to the incident form attributes from the iframe to set some values

How can i do this?

Thanks

Regards