Can't choose program when i edit task sequence

Hi,

following problem:

I want to edit some OSD task sequences because i got a new version of Symantec Endpoint Protection from our central IT department.

I first created the new software package and created a program 'Installation silent' which runs setup.exe.
Added both 32 and 64bit version to my DPs.

Then i edit OSD task sequence and add Install software. I then browse to my created package and choose it. But i can't choose a program. The dropdownlist is empty, a red exclamation mark is showing. 

SCCM V 4.00.6487.2000, R2 installed, Windows Server 2008 Standard, SQL Server 2008 Standard

Please advise!

TY, Pep