Try the following simpler code:
In[95]:= function = Integrate[b x^2, x];
out = Row[{"The answer is: ", TraditionalForm[function]}];
TextCell[out, CellFrame -> True]
Out[97]= TextCell[
Row[{"The answer is: ",
TraditionalForm[Rational[1, 3] b x^3]}], CellFrame -> True]
