UnloadApp HTTP Administraton Command is not Working.

Hi,

I am calling this UnloadApp Command through HTTP but I am keep getting this "NetConnection.Admin.CommandFailed  5/30/2017 2:53:04 PM"

My URL Is

localhost:1111/admin/unloadApp?auser=Arslan&apswd=Arslan&appInst=livepkgr/_definst_

Below is my Users.xml I have already allowed command

<AdminServer>

        <HTTPCommands>

            <!-- Enable or disable using HTTP requests to execute admin commands.     -->

            <!-- Set to "true" to enable, otherwise it will be disabled.  The           -->

            <!-- actual commands permitted for server admin and virtual host admin    -->

            <!-- users can be set in the Allow and Deny elements.                                       -->

            <Enable>${USERS.HTTPCOMMAND_ALLOW}</Enable>

            <!-- List of server admin commands that can be accessed via HTTP.         -->

            <!-- Add multiple commands separated by commas.  "All" indicates          -->

            <!-- every command (it's not recommended to allow all commands).          -->

            <!-- Seperate multiple commands with commas.                              -->

            <Allow>Ping,unloadApp</Allow>

            <!-- List of server admin commands denied access via HTTP.                -->

            <!-- Add multiple commands seperated by commas.  "All" indicates          -->

            <!-- every command.                                                       -->

            <Deny>All</Deny>

            <!-- Processing order for deny and allow command lists.  "Deny,Allow"     -->

            <!-- means the command will be allowed if the command is in the allow     -->

            <!-- list or not in the deny list.   "Allow,Deny" means the command       -->

            <!-- will be allowed if it is in the allow list and not in the            -->

            <!-- deny list.                                                           -->

            <Order>Deny,Allow</Order>

        </HTTPCommands>

    </AdminServer>

Can you please tell me what I am doing wrong ?

Thanks!