Miter Trim

I am having a problem completing a Miter Trim in Solidworkd 2013.  In my previous version I was able to miter two different weldment items regardless of the plane and now when I try to complete a Miter Trim of two elements I am getting and error or warning stating "Only Linear Structural Members can be used to do a Miter/Butt Trim."  Why in this newer version of solidworks am I no longer able to complete this function?

Angie

SolidworksWeldments