Putting Dinah's box situation aside, Yaakov wasn't punished for taking multiple measures in preparation of his confrontation with Esav.  He should have just prayed, but he also sent gifts, separated his camps, etc..

One answer to this is that we learn from here that hishtadlut is important alongside prayer.  So then, why did Yosef get punished for asking the winemaker to remember him? (According to Rashi)