Issues with modelling angle section as a cantilever

Question

When modelling a single angle as a horizontal cantilever, (along x axis for example). I applied a beta rotation of 45deg to get the leg vertical and applied a vertical point load at the tip. Following a successful analysis, the resulting deflection appears to be incorrectly calculated by STAAD compared to hand calculation, the value of vertical deflection is higher than calculated value, and there is an out of plane deflection (Z axis) that should be zero. I could not find a STAAD verification example for this problem. If any one knows why this is happening and offer a solution would be appreciated.

Sye · Answer

I assume you modeled an equal angle as otherwise a 45 beta would not make the legs parallel to the global planes. Also which deflection are you checking ? Is it the Node displacement value from within the Node Displacement table ? If you can upload the model and provide details of how you are calculating the displacement, we can take a look.

Sye · Answer

Here is how the displacement is calculated. To begin with, I would like to mention that the software considers the deformation due to shear which is neglected in the hand calculations and so to make the STAAD.Pro value match with the hand calculations, I have added the command SET SHEAR to the file. 
 
 The modified STAAD.Pro model is attached for reference 
 angle cantilever_modified.std