When you specify a jar file with a relative class path in the collect command and later run er_print from a different directory, er_print is not able to find the jar file references saved in the expriment - so you see the errors.
There are two solutions to the issue:
a) Run er_print in the same directory where collect was run to capture the experiment so the relative paths get resolved correctly.
b) Add the following to <dot>er<dot>rc ( .er.rc )
If you had multiple jar files you could specify as follows:
Note there can be a .er.rc in two locations
a) The home directory
b) The directory from where you run the analyzer (i.e. er_print) (the current directory)
The current directory takes precedence.
This will allow er_print to pickup the jar file from the correct location and report correctly.