how to insert a block within a cck input form in Drupal 7? I wanted to insert a block within the CCK input field in drupal 7. I have created a block which would display all the custom content types and the nodes created with those content type in tree structure and categories,sub categories from Magento. The tree value is dynamically populated every time.

I want to display this tree in the cck input form to enable the user to make the selection. I was trying to do this using hook_theme in hook_form_FORM_ID_alter. I used module_invoke to insert the block module within the module template file. but its look like I cant insert the block within the template.
Could anyone tell me why I module_invoke is not working and suggest me a way to insert this tree in the CCK input field. I want to get the value selected in this field and store for use in some other module.
So you're block is created and working?  You just want to insert it as a field?  You can do that using Display Suite, or if you want to insert it within a text field you could try Insert Block (still in dev)

I think Display Suite is the way to go, it is a very comprehensive module so it takes time to take it all in, but it provides very intuitive solutions for Drupal shortcomings, such as displaying a block as if it were a field.