add a button on the tab of products (customer quote)

Greetings ,

I need to add a button on the tab of products (customer quote), the button will execute a web service that will bring colors for each existing position on the grid of products, I added a new node in the items node of xbo customer quote called colors ,

which contains two fields will be completed for each position according to the colors you get from my web service, after for each position i add ovs, this ovs get the colors for each position , the problem is when I created my action on the item node ( xbo customerquote ) and then using the UI Designer and select button group , add action and activate my cod_quote_ti screen,

I my screen c4c customer quote of the web , the button is disabled and do not understand why,

please could help me on how to do that or give ideas, thank you very much for responding.