SDL Studio 2014: Error message - Sequence contains more than one matching element | Sequence contains no matching element

Forum: SDL Trados support
Topic: SDL Studio 2014: Error message - Sequence contains more than one matching element
Poster: Justinaseniut
Post title: Sequence contains no matching element

hello,
When I highlight corresponding words in both source and target languages I get error "sequence contains no matching element". Could anyone help me solve this problem?