Problem with custom sharepoint designer approval workflow - check box: 'Start this workflow to approve publishing a major version of an item' is greyed out

Question

I wanted to create a simple approval workflow. Hence I opted to start from scratch rather than copy the OOTB approval WF. Using SharePoint Designer (not Visual studio) I created a reusable workflow and have added the built in 'Start approval process' action.
It's saved and published globally.
Everything works fine except that when associating the WF with a list the 'Start this workflow to approve publishing a major version of an item' check box is disabled.
Major and minor versioning is enabled for the library.
What am I missing here? Or do I have to start from the OOTB approval WF to get this to work?
Regards
Henning

Answer 1

Again - new ideas pop up right after defining the issue as a problem. :-) Problem solved!
I solved this by creating a new workflow from the original publishing approval workflow (copy and replace), but instead of tweaking the already defined approval process (WF action) I deleted it, then deleted all initiation form and local variables,
and then added the 'Start approval process' action again. This re-installs all the necessary local variables without any initiation form involvement, which is just what I want.
From here I can tweak the workflow to make it more user friendly, much like
described by Bobby Chiang in his great blog.
Remember to add action Set Workflow Variable 'EnableContentApproval' to Yes right before the Start Approval Process action, else the document's status won't be set to 'Approved' or 'Rejected' as an output of the workflow.
Learning every day!
Henning