[Tex/LaTex] Question marks showing up while trying to reference equation


Similar questions have been asked, but I've found them to be of no help. When I try to reference an equation in texstudio, all I get is ?? An example of code I have inserted which does this (I have taken this from Wikipedia) is:

\begin{equation} \label{eq:solve}
x^2 - 5 x + 6 = 0

x_1 = \frac{5 + \sqrt{25 - 4 \times 6}}{2} = 3

x_2 = \frac{5 - \sqrt{25 - 4 \times 6}}{2} = 2

and so we have solved equation ~\ref{eq:solve}

Instead of it displaying a number I just get ??, and yes I've compiled more than once.

For completeness I'll include the beginning of my code:


Best Answer

You need to specify the option amsmath (in addition to the option thmmarks) when loading the ntheorem package. (See also section 3.2.1 of the user guide of the ntheorem package.)

Related Question