Thanks for the replies.
I've looked at the test strips in different lights. The test area is a shade of green but there is no green in the comparisons.
I've written to the people I bought it from (homebrewcentre.co.uk) and will let you know what they say.
I wanted to start brewing this...
I've just tested two types of apple. One is sweet, the other more sharp.
Neither produces a colour that can be compared on the test strip.
See the attached photo.
Any ideas?