错不了。（cuò bù liăo.）It is unlikely to go wrong.

Explanation

“错不了”表示对自己猜测或言行的一种肯定。”错不了”经常用作补语或者作为插入语使用。
“错不了(cuò bù liăo)” is usually used by someone to affirm his/her own guess, statement or behavior. It often acts as a complement or a parenthesis.
Words:

担心dānxīn:worry;
顺利shùnlì:smoothly;
合作hézuò:cooperate.

Sentences

1、Jiă: Wǒ hěn dānxīn zhè gè xiàngmù néngbùnéng shùnlì wánchéng.
甲：我很担心这个项目能不能顺利完成。
A: I worry whether the project can be finished smoothly.

Yǐ: Fàngxīn ba, xuănzé hé zhè gè gōngsī hézuò cuò bù liăo.
乙：放心吧，选择和这个公司合作错不了。
B: Take it easy. It is unlikely to go wrong to cooperate with this company.

2、Jiǎ: Nǐ quèdìng wǒ de shǒujī shì bèi Xiăo Qiáng názǒu de?
甲：你确定我的手机是被小强拿走的？
A: Are you sure it is Xiao Qiang who took my phone away?

Yǐ: Cuò bù liăo, wǒ qīnyǎn kànjiàn de.
乙：错不了，我亲眼看见的。
B: Definitely. I saw it with my own eyes.