Searching in Kobo Reader.

Hi,
I have some troubles searching for a word in all my Kobo readers. Some times it works and some times not.
I press the search icon and select "Current Read".
I then enter the word and press "Go" and very often, but not always I get "o results found."

I intended to use it on a persons name in order to refresh my memory.
To be specific I searched on the name "Palfrey", no results.
To test I tried "heathrow" many results,

"junior" no results
"boy" many results.

I am of course sure that all the words exist.

Works very well in the Calibre Reader.

Any ideas?

Edit: Works fine in Kindle Oasis.