LyX ⇒ error "Layout `Theorem*' was not found."

[Cosm]

I would like to number the definitions, theorems etc. separately like this for example:
DEFINITION 1
THEOREM1
DEFINITION2
COROLLARY 1
ETC.

So in Document Settings Modules I selected the "Theorems (Numbered By Type)". But I get the error "Layout `Theorem*' was not found."
I put the \usepackage{amsmath} in the preamble but this didn't help. What should I do?

[Cosm]

Strangely this problem fixed itself, I really don't know what I did. So I guess there is no problem then.