GAD 7.6.2 Simple Custom Button not working

[edrinthomas]

We are using GAD 7.6.2. My team has added a new button to custom.xml as per the example in "Genesys Desktop 7.6 Developer’s Guide" page 35,36. But the button is not getting displayed. The whole TAB(chat window) is displayed blank.
And also all other customization (like customs TABs) are working without the button code in the custom.xml.

I got a log from GAD

27 01 07:25:15:585 [nesyslab.PCT.invoker] DEBUG Ail.Omsdk.Driver com.genesyslab.platform.commons.protocol.ChannelEr rorEvent[source=com.genesyslab.platform.openmedia.protocol. InteractionServerProtocol@54f169@{GAD - tcp://XXX.XXX.com:8888}]; cause: com.genesyslab.platform.commons.protocol.MissingAt tributeException: Attribute is not accepted by the message. (109 in 189).ChannelListener: channel error

is this normal??

Can someone guide me to troubleshoot this problem.

Thanks in advance.