The following code correctly produces 9, 10, and 11 as the Lemma labels but 6, 6, 11 when the references are printed. What could be causing this? (6 happens to be the chapter number.) All the other cross-references seem to be correct.
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsfonts}
\newtheorem{exercise}{Exercise}
\newtheorem{lemma}{Lemma}
\begin{lemma}
\label{L-t-abs cont incr}Suppose that ... functions.
\end{lemma}
\ref{L-t-abs cont incr}
\begin{lemma}[Lebesgue, 1904]
\label{L-t-LDT}If... $\left[ a,b\right] $.
\end{lemma}
\ref{L-t-LDT}
\begin{lemma}
\label{L-t-constant}If ... on $%
\left[ a,b\right] $.
\end{lemma}
\ref{L-t-constant}
{}button, as in my edit. Also it helps if you could edit your example to be a complete document that shows the problem. – David Carlisle Mar 22 at 17:32\documentclass{report}and\chapter{aaa}then it works for me giving references 1 2 3 – David Carlisle Mar 22 at 17:37