Why do I get amplification curves for my qPCR run without a template?

I have been getting contamination in my PCR reactions. Because I could not eliminate the contamination internally, I bought new a pipet, new filtered tips, new SYBR, new water and new primers. However, I am still getting the unexpected amplification curves in my reactions! I am using primers (25nmole DNA Oligo) from Life; PCR water from Ambion; Power SYBR Green PCR master mix from Applied Biosystems. On the master mix bottle there is a label saying: PCR master mix (2X). Before using SYBR from Applied I used to use master mix from Qiagen. Can the new SYBR produce false positive results? If yes, why? Can anyone help?