Not able to retrieve data from telemetry server for Prometheus pull request

[sba429]

We have one c++ application running on telemetry (civet server ) at port 5055 and it collects all the metrics of application.
Now when I send a pull request from a Prometheus server i.e; simply we are placing a GET request as "http://localhost:5055/metrics" for viewing metrics data, it is able to connect properly and no Error is showing up, but no metrics data is being retrieved . What can be the possible cause of this issue ?
Can somebody help with any sample program for retrieving metrics data from c++ application for Prometheus exporter ?

Please refer to the following screenshots.

• Screenshot of Prometheus server status
  

• Screenshot of c++ application server ("http://localhost:5055/metrics")