How to pass dynamic parameters to Rest API

Summary:

I have added an End Point in VBCS which is based on VBCS BO with GET operation. Upon pressing Test it is returning records as well. Now I have added one dynamic parameter to enable search mechanism. After creating one dynamic parameter and passing a value to it I am getting below error:

{

  "type": "HTTP://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.1",

  "status": 400,

  "title": "Bad Request",

  "detail": {

    "title": "Bad Request",

    "status": "400",

    "o:errorDetails": [

      {

        "detail": "URL request parameter docName cannot be used in this context.",

        "o:errorCode": "27520"

      }

    ]

  }

}

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