TNS problem from standby to primary

I have a tns problem regarding dataguard.

There are 3 databases, 2 of them were successfully created (rebuild) a standby db. The third one is not. The one thing I notice about the third database is this:

I can tnsping the primary database, and the standby database from the primary.

I can tnsping the standby db from standby itself, but I can't tnsping the primary.

But I can tnsping the individual db itself, just not the main db name.

Here is some explaination

primary1, let say, have this name : PRIMARY1_SRV

primary2, have this name            : PRIMARY2_SRV

so I can tnsboth,

I can also tnsping PRIMARY.