Abaqus - isotropic material definition problem with engineering constants

Hi, 

I am using a steady-state dynamic analysis procedure to model harmonic loading of a structure. I am investigating different material definitions. When I applied transversely isotropic stiffness using engineering constants, I saw a much different response than expected. So, as a test, I compared the following two models which gave DIFFERENT results: 

1) Simple cylinder with linear elastic, isotropic material properties (E, v), structural damping (0.05) and density of water. 
2) Same structure with linear elastic material defined by engineering constants which are ISOTROPIC (i.e. E1 = E2 = E3 and v12 = v13 = v23 and G12 = G13 = G23), structural damping (0.05) and density of water. 

In the models, E (from model #1) = E1=E2=E3 (from model #2) and v (from model #1) = v12=v13=v23 (from model #2). I have verified that all other aspects of the model (element type, bc's, load, etc.) are all exactly the same. 

So, why do the wave propagations look so different different? 

Thank you for your help. 

Renee