I have a custom action in a formula field using the following code:

"<a class='zc-formbutton' href='#Form:Approve?zc_LoadIn=dialog &Vendor_ID=" + Vendor_ID + "&Request_ID=" + Request_ID + "&RFQ_Response=" + input.RFQ_Response + "'  >Select as Winner</a>"

Immediately after saving this code the input value of RFQ_Response is working and the form that opens up has the proper value in the RFQ_Response field.

Trouble is, if i edit the button or save the form later the code on the custom action seems to change and stop working.  The input. is removed and the script changes to the following:

"<a class='zc-formbutton' href='#Form:Approve?zc_LoadIn=dialog &Vendor_ID=" + Vendor_ID + "&Request_ID=" + Request_ID + "&RFQ_Response=" + RFQ_Response + "'  >Select as Winner</a>"

Now if i go into a record and click this custom action button the proper value is not retrieved.

Why is this happening and how can i fix this?

Is this a matter of needing to build a function instead of the formula field with code in it?