Why do I get amplification in a negative control DNA tube using the REPLI-g Kit for WGA?
FAQ ID -675

Phi29 DNA Polymerase has an extremely high processivity and will extend primer-dimers that may be present in the reaction, leading to unspecific amplification products. Furthermore, the REPLI-g reaction is highly sensitive to any traces of DNA. Even minute quantities of contaminating DNA from other sources are eventually amplified over the long duration of the reaction (6-16h). However, these non-specific products will not generate specific results in downstream genetic analysis.