I am using the composite beam design capabilities. But the output does not show any evidence of this design. Why?

There are 2 sets of data associated with analysing and designing a composite beam.

Step 1 : Define the member properties as a composite beam. To do this, one has to use the "TA CM" option as explained in Section 5.20.1 of the STAAD.Pro Technical reference Manual. For example, if member 1 is a composite beam made up of a 3.0 inch thick slab on top of a W18X35, and the grade of concrete is 4.0ksi, one would have to specify

UNIT INCH KIP
MEMBER PROPERTIES
1 TA CM W18X35 CT 3.0 FC 4.0

Step 2 : Parameters for steel design. This is what you find in Section 2.9 of the STAAD.Pro Technical reference Manual. These are the attributes which are to be used in the actual design equations, using the expression PARAMETER, as in,

PARAMETER
CODE AISC
BEAM 1 ALL
TRACK 2 ALL
FYLD 50 ALL
CMP 1 ALL
DR1 0.3 ALL
WID 60 ALL
FPC 4 ALL
THK 4 ALL
SHR 0 ALL
DIA 0.75 ALL
HGT 4 ALL
RBH 2 ALL
CHECK CODE ALL

The most important thing to note here is the usage of the parameter CMP. Unless it is set to 1.0, STAAD does not design the beam as a composite section. The beam will be designed as a pure steel beam section in the absence of the "CMP 1" parameter.