Internal cross reference to theorems

[bohungi]

In book Sequences and Series', working on sectionSequence limit via horizontal asymptote'. Trying to create internal cross reference to Theorem: `Sequence limit from function limit'.

Trying to add label fails; the system does not remember my input.

Trying to create internal cross reference to that theorem fails with error message 'Create label first'.

[bohungi]

Caused by limit of label length to 30 characters. This limit has now been set to 128 characters