If you are able to locate the .psm symbols in the PSMPATH then you may be missing the padstack/shape symbol associated with the package symbol you are trying to place. Place the symbol directly from the library and check for any messages on the Allegro command line to see if it reports any padstacks or shape symbol that it could not find. Place non-netlist based symbols from the library as follows:
1) Place > Manually...
2) Under the Advanced Settings tab check Library in the List Construction section
3) Under the Placement List tab select Package Symbols from the Pull down and select the symbol you are having problems placing.
Give this a try and see if it gives you any hints on the issue.
Hope this helps,