Error message: Can't find design entity "..."

[Altera_Forum]

I have a design containing both *.bdf and verilog files. In the hierarchy, when I click on a bdf module (XP running Quartus v10.1), I get an error window: 

 "Can't find design entity ..."   where "..." is the instance of the bdf module.   The design compiles just fine and I have access to all bdf files by just opening them directly in the directory they're in. Verilog files don't get this error message. All bdf files are listed as project files.   I recently installed 10.1 and didn't have this problem prior to that with exactly the same design.   This has to be a simple fix, but I don't see it. Any suggestions?   Greg

[Altera_Forum]

I have a similar issue with Quartus V9.0sp2.  

Although I've not verified it, I thought of this possible cause: When I create a new symbol in a design, then I can always open with hierarchy. If I copy and add the module files to another project, then hierarchy is not recognized, although compilation always succeeds, as in your case. I can reactivate hierarchy if I force a create symbol. My supposition is that the hierarchy information is stored in the project file or in project library when I create the symbol, so it is lost if you simply copy .bdf .qip. .vhd .v files and add them to the other project.

[Altera_Forum]

I found similar issues in two cases: 

1) using legacy symbols from maxplus2 directory 2) trying to simulate designs including LPM_* symbols moving from QII9.1 to 10.1  In both cases a workaround was to eliminate the bdf from the project and just synthesize and simulate the HDL files  Fpr the case 1) also a slight change of the HDL files has been needed.  Hope it helps.

[Altera_Forum]

--- Quote Start ---  I have a similar issue with Quartus V9.0sp2.  Although I've not verified it, I thought of this possible cause: When I create a new symbol in a design, then I can always open with hierarchy. If I copy and add the module files to another project, then hierarchy is not recognized, although compilation always succeeds, as in your case. I can reactivate hierarchy if I force a create symbol. My supposition is that the hierarchy information is stored in the project file or in project library when I create the symbol, so it is lost if you simply copy .bdf .qip. .vhd .v files and add them to the other project.  --- Quote End ---     I tried recreating symbols and replacing the old ones with no luck. The odd thing is that in the navigator hierarchy, you can right click on a bdf, select properties, and there you can see that it has the correct directory address for that bdf. Also, in the navigator under "files" and "design units", it can launch the bdf . I can also right click and successfully use the "locate" option for a bdf. Clicking on bdf symbols in a bdf window to go down the hierarchy works too.