Hi Mat,
Your data source in 3.x. You need to migrate to 7.x by using T code - RSDS, menu data source--> migrate 3.x to 7.x.
Once you migrate data source to 7.x then you can easily create dtp.
Red mark --TRCS 0WBS_ELEMT_CRM_ATTR-->IOBJ OWBS_ELEMT (its in 7.x version, no blue dot mark)
Green mark - 0WBS_ELEMT 0WBS_ELEMT_ATRR(Its in 3.x and have blue dot mark) - so here dtp not possible.
So migrate your data source to 7.x and then create dtp. it will allow you.
Thanks