Recursive definition problem when extracting real part of equation

Hi everyone,

For my thesis work I am building a tool to evaluate the notched stress field in orthotropic fields. For this I need to extract the real part of an imaginary function. However, when I try to take the real part MathCAD 14 returns "recursive definition"-error. No idea what is going wrong as the variable has not been defined.

Can you find out?

Many thanks,

ruben