Issue with transaction codes

Friends,

I'm new to SAP & XI.

I tried to excute transaction code XK01/XK02/XK04 but gets "Transaction "XXXX" does not exist.

I'm having issue with majority of Transaction codes. (Customer, Vendor etc)

When I tried to run WE05 to see the IDoc list but I keep getting "No IDocs selected" doesn't matter what search criteria I give.

I appreciate any help on this.

Thanks,

Hetal