Different Price/Rate for resources in resource assignment

Hi All,

I faced with a problem during resource loading in a schedule, I created some resources the Price/Unit for all is 1$/d as shown in the below screenshot:

I don’t have any other price/unit for such resources, for most of the activities it works so in the activity resource assignment it shows Price/Unit equal to 1 however for some activities (all activities Under 1 specific WBS ) it Shows 3$/d for price/unit instead of 1, actually it always multiply whatever I have as price/unit for the activity by 3. 

This happens for any resource that I assigned to such activities.