PCR product (SmaI) site

[A Al-dukhyil]

Dear everybody,
I wonder if any one could help me in this problem:
I did PCR by using Vent Pol. for a gene of 2Kb with insertion of SmaI 
site near 5'end. I got good PCR product then I inserted this product in 
PBR322 plasmid (EcoRV) site. I had the right size 6.3Kb BUT,when I cutted 
with SmaI I got uncut plasmid. I hope to find good solution for this 
problem.
Note: SmaI enz. has been tested and it was alright.
Thanks for helping