lowpoly tree problem

hello,

i added these cool lowpoly trees to my scene (i little village) and there`s a little problem with the shadows.
the tree consists of a mesh trunk and planes (with a leave-texture with alphachannel as background on it). in the .blend file the trees were from the lighting works (the texture on the planes casts shadows as it should). in my .blend the shadows are not cast from the texture on the planes. they are cast from the planes itself. so i have angular shadows instead of nice blurry shadows.
and i just dont find the little button to switch on/off the feature that these textures cast the shadows and not the planes there are on.

so could youi please help me with this little problem?
thx for reading

EDIT: i already searched for problems like this and found some stuff… but it didnt work (UseAlpha, Ztransp, map to alpha, …)

i found the problem… turn on trshadow on the shadowRECIEVING plane…

thanks for reading…