Clumping cat litter – not successful!

Tried some ‘Fuller’s Earth’ clumping type cat litter. Not a success! Large, clay like, lumps had to be removed. Horrid! Now gone back to previous wood chip variety. I think there are some excellent clumping varieties of cat litter – but the best are, I fear, rather expensive.   We will have our ‘indoor’ cats for many years, so the cost of this stuff is somewhat significant.