Please advise as to what might cause an injection error. Because I am just beginning in this field, please advise( if you can) what literature I might find to list or discuss possible reasons for injection errors.

Thank You.

If you do not have access to "Dolan and Snyder, Troubleshooting LC Systems, Humana Press, . . .", try a keyword search of this LC MESSAGE BOARD. You could also browse the net, for instance, www.alltheweb.com.
In short:
-If you fear overlading, just reduce the amount of sample and observe what happens.
-If you inject too much volume proceed likewise. If needed concentrate the sample.
-High volume injection are often ok if the sample solvent is of lower eluting power as the MP. Only very small volumes may be injected if the sample solvent is more strongly eluting than the MP.
-Check by injecting H2O, etc., whether you have carryover. If yes, you have to systematically search for the source. The syringe and injection valve are the most common sources.
-Make shure the injection loop volume does not cause trouble regarding the amount of sample reaching the column.
-The waste exit of the injection valve should be ~level with the entrance port in Rheodynes, if the exit is lower liquid can run out and pull air onto the loop in "inject" position.
-Make sure that liquid comes out of the exit during loading.
-De-gas the the sample if you get a broad unexpected peak.
(-In other words: play, observe, think of and try corrections)
If you still have problems, please post a precisely formulated question to the forum.