TeXShop ⇒ No Pop-up Menu for Citations and Cross-references

[takpol]

when I typed "\cite{}" or "\ref{}" I used to get a popup list of all bibliography items resp. all labels in Texshop. This doesn't work anymore. I have tried deleting all aux and bbl files in the folder but it did not help. Also I have tried to change some of the Preferences that I thought are related but was not helpful.
I do not use Bibdesk. I know that it is another good way of organizing references, but I just have .bib file that I open with Texshop and I had quite a smooth time using \cite{} menu to choose from my references before. Did anybody have that problem?
Thanks
Takpol