Dose - Was it bunk(bad) acid?

[fluffhead]

SWIM went to a festival last weekend where he found some lsd. SWIM ate a half tab of the all-white tab and felt nothing. Hours later he ate a full all-white tab and still felt nothing. One day later SWIM found a different batch, these tabs had small black designs on them, and he repeated the process. SWIM ate a half tab and felt nothing and hours later he took a whole tab but still nothing. SWIM was told that the tabs with black designs on them was strong and to take no more than one tab. SWIM is nervous to take too much, but is curious as to why he isn't achieving any effects. Is he getting ripped off with bunk acid or is he ingesting it the wrong way? He said he held the tabs under his tongue for about five maybe ten minutes and swallowed. Any advice would be great, thanks.