This has nothing to do with whether the Caps Lock key is on or whether you're using All Caps but with whether you're calling the output content control with the correct name in the code -
CLIENTDETAILS
is not the same as:
ClientDetails
In the code, the names are case-sensitive.

As for capitalising whatever the ClientDetails control displays, that can be accomplished by changing:
.Range.Text = StrDetails
to:
.Range.Text = UCase(StrDetails)
though you should, perhaps, be capitalising whatever you're inputting into the 'Client' content control to begin with.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]