Customising sharepoint Workflow Task List

Hello guys,

 

I want to customise my workflow task list (using visual studio) but unfortunately i cannot access to the default list, so i’ve tried to create a new one (with a task list type) and when I’ve tried to create a new workflow I’ve used the new customized workflowTaskList but it doesn’t work and I didn’t get the problem here do you have any idea please? any help would be appreciated and thanks in advance.