Hi,
did you already check table RSBASIDOC? Is the connection available in your source system in that table? If not, restore the connection in BW (RSA1 --> SRC --> restore). As the system should automatically create a missing Idoctype during the restore, I would delete the manual created Idoctype.
If the connection is ok, also check transaction we20 --> RSSEND if the correct 'BASIC type' has been assigned.
Manual check of a source system connection is described under:
How to check a BW - SAP source system connection - SAP NetWeaver Business Warehouse - SCN Wiki
best regards,
Janette
