Inline and Multi-line equations fail

[Benedikt]

Hey,

I have been trying to get following multi-line equation to work:

.. math:: 

   

   P_{Survival} (L) = P_{S} (L) = exp \{ - \frac{ \sigma (E) \rho L}{m_{T}} \}

   

   P_{Interaction} (L) = P_{I} (L) = = 1 - P_{S} (L) = 1 - exp \{ - \frac{\sigma \rho L}{m_{T}} \}

They show up as one continuous inline equation instead of being a block of two equations. Individually they only work as inline equations.

Similarly, 

.. math:: 

   

   P_{Interaction} (L) = P_{I} (L) = = 1 - P_{S} (L) = 1 - exp \{ - \frac{\sigma \rho L}{m_{T}} \}

shows up as an inline instead equation block. 

Any recommendations what could be wrong?

Thanks a lot in advance.

Cheers