Help Screen capture doesn't work in Messaging

[Bad Bowtie]

Just like the title says, doesn't work when I'm trying to capture a conversation in messaging. It will take one of the list of my conversations, or if I click a "text bubble" in the conversation, in Facebook app, etc...but will not take one of my "text bubbles" in the conversation.

Any help or does it just not allow you to do that?

Thanks in advance.

 

[Mada]

I just successfully captured a screenshot inside the messaging app.