Difficult installation of a vinyl grass mat [update]

Unfortunately only two weeks after I have installed the vinyl grass mat (described here), I've decided to tear it down. I was too unhappy with the results of my work...

I've found several problem with my installation:

• As already noted in the original post, the glue did not hold throughout the entire surface. There were bubbles of air here or there. Two weeks later there were even more such places. And when the rail track was placed on top of it, it was not flat at all...
• Any attempts to fix the 'air bubbles problem' failed. I also damaged the mat even more in the process. In the end it looked much worse than right after installation...
• I had to drill some holes through the layout and... this revealed how weakly the mat has attached itself to the wood. Drilling caused even more air bubbles to appear and made the surface very "wavy"...

So I decided to tear it down. This brought another surprise, since the removal of the mat did not require any force at all. The mat was barely glued to the wood at all...

I still don't know what I did wrong. The vinyl grass mat does appear to be a nice product. Seems however, that I completely failed to install it properly... :(